They're not particularly hard to install, just read the directions carefully and take your time. One thing I remember is that the trim ring for the inside (ceiling) piece isn't all that much oversized so be careful when cutting the hole in your ceiling.

As with many things you typically get what you pay for. I've installed both Solatube and Velux brands, although it's been a while. I want to say that I preferred the Velux but I don't recall why. The extension tubes can get quite expensive so try to carefully pick the location so that you don't end up needing 5" of another tube.

They do add a lot of light and obviously the bigger the tube, the more light. What I noticed is that after installation most people walked out of the previously dark room wanting to turn off the light switch. ;-)

You do want to install them on a warm day, maybe 60° or more. You need to peel back shingles to install the flashing on the roof. If the shingles are too cold they'll snap instead of bend and that, as Martha would say, isn't a good thing.

Thanks for your advice, Mike!

we are happy with these:

Here is a link that might be useful: sun pipe

Do it! Not the simplest job, not really tough, either. But in terms of payback, very very worthwhile.

My dad put two in their family room. It only took him about 2 hours total. The results are FANTASTIC - they lit up a very deep, dark family room. It is amazing how much light they bring in to the room.