Since you're clueless, you're in the 99% of people (including myself) who would probably think they sound great. Ask your guy if you don't like them can you exchange them just to be safe.

Sounds like you have 4 Sonos Zones wth 3 in wall speaker zones. Looks like the biggest variable here could be wireless performance in your apt. and potentially your installation skillset. Technically it is not difficult to install an inwall speaker however NYC apartments present interesting challenges. You did not maention if your walls are drywall or Prewar building plaster. Also note that if your apartment is fairly large wireless may not work very well. You are actually much better hardwiring a SONOS system if you can (Setting up a LAN). This way it works best. The monies involved in what you are proposing are significant at least 1.2K or more for speakers and install materials. You should also consider small speakers such as the Monitor Audio Radius Series Speakers. They sound great with Sonos and are easy to place and setup Sonos is fabulous when setup properly. However NYC apartments are not the friendliest landscape for a Sonos system. Here is a link that might be useful: Monitor Audio Website

Questions like this always amaze me since in-wall rated LV wiring such as: speaker, coax, HDMI, video, low level audio, communication, control, and CAT5/5e/6 is so readily available, you actually almost have to go out of your way nowadays to find wiring & cable that not in-wall rated. Usually it comes up when somebody is attempting to run that "speaker wire from the 80's" through walls - that clear zip cord junk that starts oxidizing before you even strip it. In-wall rated speaker wiring, besides being proper from a jacket safety standpoint, is easier to work with, has a more durable jacket, and is much smoother to pull. And the other thing - it is usually less expensive than the cheap stuff. The NEC does not specifically address low voltage "home theater wiring" such as in-wall drops from a display device to equipment below, and in-wall connections from finished product, in residential settings, since is not always considered "structured wiring". However, NEC articles 640, 725, & 820 come closest to addressing this and would probably be what most AHJs would reference if the installation was being inspected.

That's hideous looking. The fabric for the grill needs replaced. It can't be painted. The whole grill assembly can probably be replaced. I'd start an internet search based on that.