I went to George Mason for undergrad. While that was a bit longer ago than I'd care to admit, I believe I can still say a few things about GMU.
Mason has a beautiful campus. Swaths of the campus were under construction when I was there, which removed a decent chunk of the forested area within Patriot Circle, but it's still leafy and pleasant.
GMU is definitely still a commuter school, despite the Carnegie Foundation's reclassification of the campus as "primarily residential" a few years ago. There is a solid residential "core" in the student body, but without the commuters the campus gets fairly quiet on the weekends.
Fairfax is the embodiment of suburbia. If you like strip malls and chain stores, you're well covered. There are few exceptions to this rule. I recommend traveling east to Arlington/Alexandria or DC if you want non-chain places.
On the subject of DC, it's close and has tons of connections with GMU, but if you live on or near campus it can feel farther away than it actually is. If you want to take public transit to get to DC, you have to take a bus to the metro station and it ends up taking about an hour and a half to get there. I recommend living close to the Vienna metro station, if possible. When I was there, parking at Mason was more of a rite of passage than a convenience, but they've built a number of new lots since then.
There are a number of places to study on campus if you can study with ambient noise. The JC (Johnson Center) alone has a ton of great spots. The only quiet indoor study space is Fenwick Library. I logged hundreds of hours at Fenwick. Also, since GMU is a member of the Washington Research Library Consortium, you can borrow books from G'town, GW, American, etc.
The Center for the Arts is beautiful and you can get free tickets to all sorts of performances from the Virginia Opera to Rockapella (wooo '90s kids).
A couple of GMU's best qualities are difficult to quantify. First, Mason students take pride in the diversity and inclusivity of their university community. GMU is a young university, which means experimentation is encouraged. I've also studied at another Virginia University that is bound by Tradition, which showed me the value of an academic community that doesn't have those hang-ups.
Finally, I'll just say that I really enjoyed my time at Mason, but it's important to leave campus (and Fairfax) and take advantage of GMU's proximity to DC.