Above commenters (especially the amazing detailed posts by jpg and acindc82) covered this well, and I just want to agree with their overall assessments. I’ve rented a 1BR condo in Brookland for 6 months now with my girlfriend and our dog (after 3 years mainly in Adams Morgan and Mount Pleasant), and I’ve really loved it. The neighborhood is definitely much safer than Columbia Heights and Adams Morgan (see this map, for example: http://danieljwood.github.com/DC-crime/index.html ), though it also has many fewer walkable restaurants and retail options. One thing jpg may have overlooked is the numerous mid-sized apartment and condo buildings around 12th and Perry, including Oak Terrace (condos that many owners rent out), “The Perry”, and a few others. I live around there, and the combination of short walk to metro, low rent, pretty tree-filled neighborhood in which to go running, and nearby YES Organic Market simply cannot be beat. I know YES is generally “overpriced” but I don’t mind paying an extra $1/pound on my produce for the convenience of having it on my doorstep; I just do one big run to Giant (one stop away on red line at Rhode Island Ave) every 2-3 weeks for everything but the produce. With the red line right there, my commute is shorter than it ever was in Adams Morgan and Mount Pleasant, and it’s still fairly easy to get across town via all the H2-family of buses that go east-west and terminate at Brookland station. One amenity unmentioned above is the Metropolitan Branch Trail, which is easy to get to by bike from most of Brookland, and takes you to Union Station, from which the Capitol is an easy sidewalk ride, if you hate on-street biking. Catholic University’s campus is open to wander around, and they make for a quiet, pretty place to hang out and read a book, or to go for a run.
All in all, it is one of DC’s best kept neighborhood secrets. The chief downside is that it is definitely on the quieter side, with more limited retail and nightlife options as explained by other commenters, but even speaking as someone who “thrives on the buzz of the city,” I think the abundant transit connections to the busier nightlife neighborhoods in downtown and inner northwest make it perfectly compatible with a fairly active going-out life. Though man, you should keep a good book with you on the weekends while all this track work is going on if you are gonna use Metro.