GP resident here. I really like living here, for a lot of the reasons the other people mentioned -- very green, safe, quick commute to downtown (plus easy access to Wisconsin, Mass, RCP, Whitehaven, and MacArthur) or other areas of the city (as well as National Airport). LOVE being able to walk to WF and CVS, esp in the summer, plus a brand new Safeway is very close by. Also Surfside, Max's Ice Cream, Kavanaugh's for pizza, etc. Great park (and I can swing by Starbucks on the way), plus Stoddert's brand new playgrounds.
The best thing, though, is the neighbors. There are tons of other families with kids. In the summer evenings, I just take DS out on our front steps and there are always at least a handful of other young kids around. Parents chat; kids play; it's lovely.
Cons are that parking is terrible, the backyards tend to be small (if at all), and the houses are quite small. (It seems like a lot of the families that stay with older kids are foreign families where smaller housing is the norm.) We don't have issues with students partying, but maybe other blocks do. Metro proximity might be nice, but we'd probably be priced out of the Metro were closer.

I also wish we had a library within walking distance.
Sure, it could be a bit more lively. But then it would probably be more crowded, higher crime, etc. GP is cozy, familiar, and friendly and I feel very lucky to have found such a great place.