Probably the biggest disadvantage is that eucalyptus is not fully hardy in most US gardens. The second is that where it IS hardy, it is often considered an invasive species or a fire hazard or both.

People have tried growing Eucalyptus for ornamental and timber purposes in the southern United States, but a major limiting factor is frost hardiness, even in areas that don't generally get colder than the trees' native habitats in Australia and Tasmania.

The problem is thought to be that southern states are prone to periodic cold snaps in which the temperature drops rapidly - say, after a mild stretch in autumn when temps might plunge into the 30s or colder. Even mature trees can be heavily damaged or killed, since Eucalyptus species tend not to harden off very well in fall.

E. gunnii is an interesting species for use in cooler temperate gardens. It won't survive as a tree, but often returns as a perennial.

Here is a link that might be useful: Eucalyptus in the South

Parts of Britain, where original poster is located have been able to grow large, lingering specimens. What part of Britain is being talked about is critical to the subject, hardiness zone range there is 7-11.

I live in San Diego, California where eucalyptus can be found proliferating in the canyons in the city alongside the Washingtonia robusta palms. They lose branches in a strong wind, drop a steady rain of leaf litter year round, along with shedding bark and seed pods. This, combined with their rapid growth to serious height and girth make them a less desireable tree for our small residential properties. However, in a more open setting with room to grow (and perhaps the "right" species) they provide a graceful canopy and accent to the skyline.

View of Balboa Park in San Diego and eucalyptus skyline (photo sourced from web):

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These trees do have a negative reputation when it comes to fires, the scourge of southern California. However, the truth is the fires are so hot and so fierce, *everything* burns, so the 'fire hazard' rap may be undeserved.

I use it in my garden, backed by a Cryptomeria and mingling with a humongous Lantana 'Miss Huff'. (I think mine is E. neglecta). It remains unscathed unless it dips below 0 degrees F). Even if the foliage is killed above ground, it can be cut off and typically resprouts in the Spring. Regardless, we cut it back to the ground every 3-4 years to control its size and maintain fresh glaucous foliage.

We had 20-some E. globulus and one E. citriodora in the back area. The E. citrodora was dying of a lerp infestation, and when it was windy, would thrash against the neighbor's house. The E. globulus dropped a constant torrent of litter, including a sticky, staining gum.

We cut them ALL down, and have been much happier since. As a wind break for citrus orchards they are beautiful. Too large and too dirty for residential properties. Here's a post I wrote about getting rid of our Eucs:

Here is a link that might be useful: we got rid of the Eucs

I'm always torn when students turn to forums for help doing projects. Often that help comes from people who did their projects without such help when they were students! For the sake of the student's own learning, I hope most of this will by taken by the student as a jumping-off point for further study, and not passed of as answers on its own.

KarinL

What? You mean the teachers didn't have the answers being handed to them on a platter via the internet in mind as the way for the kids to go about it?

Not saying that is the case here, have no idea.

It's not like this is a test question and the OP is looking for answers. He/She asked for opinions on the advantages or disadvantages of planting them in a residential garden and it seems to me that asking for those opinions on an gardening forum with an international audience (potentially) is a rather creative way of obtaining a diverse yet well-rounded response. How appropriate to the issue that international response may be is the question.

It also seems like a lot of the original posters never bother to reply to the original post and responses these days. If I had realized that the OP was from England, I would have suggested that getting replies from British growers of Eucalyptus would have been better for his intended purpose. I guess the National Diploma of Horticulture wording should have tipped me off.

If for no other reason, I love looking at the outlines of canopy Eucalyptus trees from a distance, Kim's picture of Balboa Park captures this very well. There is nothing quite like Eucalyptus trees to give that sort of tracery against the sky. I love to look at them from a distance, but there are very few species that I would actually want in my own garden, mostly for lack of space and cleanup of debris issues.

If the student is young, I think a question on a forum that has a diverse group of participants makes sense - it takes time to learn about how plants perform in various environments and how various people respond to them. If the OP is young and starting out (not necessarily the case for that Diploma...), asking for opinions on a forum is probably the fastest way to expand their knowlege base on how plants perform in a wide variety of domestic gardens. And somebody young is probably very comfortable 'talking' on the computer and likely to turn to a computer conversation as one of the first options to consider....

(It was interesting how students reacted to the 'class participation forum' in the correspondence course I took last winter through the University of Guelph. The students ranged in age from 20s to 60s. I was disappointed that there wasn't as much discussion on the forum as I expected and asked the Prof. about it. She said that the older students tended to be uncomfortable with the whole written conversation format. It became very noticeable that, in general, the pattern of participation was pretty closely aligned with age - with some exceptions!)

First, I am in New Hampshire on the edge of zone 5-4. There is a eucalypt that came with the house. I have not been able to figure out what species, but it thrives here in a bushy sort of way. It is not the most beautiful thing but the novelty of it assures it's remaining. I have never quite understood the bad press that eucalypts receive. The ones I witnessed in New Zealand were among some of the most beautiful trees I have ever seen. Rivaling our mightiest oaks and long gone stately chestnuts. As a woodworker and woodturner I appreciate the strong, lustrous, durable, rapid regeneration properties of many of the species. I realize that in places such as Madagascar they have quite taken over many native genera but, at the same time, they have provided significant income and rapid reforestation in an otherwise impoverished population prone to forest destruction. If I lived where I could grow the stately trees I would welcome them in all their divers leaf, bark, and growth habits.

Hmmmmmm.......I certainly don't want to argue with you - you would know best what it is you are growing - but I find it pretty unlikely that any species of eucalyptus will survive long term in a zone 4/5. In zones lower than 7, virtually all species, including the very hardy gunnii or archeri, will act as die-back perennials at best and in zone 5 or below, unlikely to be root hardy as well without a protected location or copious mulching.

Probably why it is bushy.

I don't disagree with you but I know of nothing else that looks remotely like it, right down to the exfoliating bark. Perhaps the 4 or 5 feet of snow each winter (or 6 or 8 the last two) is enough protection for the roots. There's only a foot outside at the moment but the temps have been teens and low twenties for two weeks and the grass is still green and the ground soft underneath. It's a dead ringer for the eucalyptus my ex planted in here flower pot this summer, red berries and all just no smell... If you held stems of both next to each other (I did) you would not be able to tell the difference except for the lack of scent.

Gums do not produce red berries. And they all do smell.

Definitely not a Eucalyptus species if it has red berries. Do you have any pictures of this shrub with foliage and berries? Eucalyptus foliage varies so much by species that the assumed Eucalyptus foliage could be anything. I would also agree that no Eucalyptus species could survive your winters, even with 6 foot of snow as mulch, in New Hampshire, unless it was treated as a summer annual and/or brought inside for the winter.

If I could I'd post a picture, but kinda mute point now as no foliage and buried in snow. Still doesn't affect my real point in how beautiful the trees are or how versatile the wood is. Which I think is more important to the OP.