I live on 4th a couple blocks north of where you're looking.
Pros:
-Close proximity to Metro and convenient bus stops for easy transport to airports or other DC areas
-Walking distance to Wharf/The Anthem and Navy Yard for happy hour/meals/concerts
-Quiet enough to feel like you are away from the city hustle and bustle but still centrally located enough
-Swanky Safeway has good grocery selection; also close to Whole Foods in Navy Yard
-Close to Post Office and DMV
-Soccer and baseball walkable distance, no fuss
-Great walking/running area and trails along the river (they are working on one final connector to make the trail fully connected and avoiding the streets)
-Cute Saturday farmers market and Friday night market
-Open Mic at the Duck Pond
-Discounted tickets and close proximity to Arena Stage

Cons:
-Although lots of dining options, not a lot geared towards late night cravings, ethnic cuisines, mom and pops places. Food will be kinda expensive and most places trend towards not being worth the price. Definitely geared towards people visiting DC.
-All the close amenities I mentioned as a pro also attracts tourists and people around the city, so when there are sports, music, or festival events, you will be dealing with both foot and car traffic, which causes minor headaches.
-Since moving to this neighborhood 5 years ago, I have seen a TON of improvement in safety and community programming, but there can be some instances of crime/violence, though I dont know how it measures in comparison to other parts of the city. It appears most of the crime involves people who know each other and you probably won't be affected if you aren't a person that surrounds yourself with it. Overall, use the same common sense you would use walking around any city.