My wife and I may be moving to a house on 49th street between Beaumont and Warrington. How is the neigborhood? It looks a little seedy just West of 49th. Is there anything in particular we should watch out for?

Buying or renting?

I moved to the corner of 49th and Warrington in August, and I haven't really had any issues to speak of. 49th does tend to get a bit of traffic, and bus/trolley noise, but nothing super-unreasonable. As far as West of 49th (at the risk of offending folks who live their, my guests often feel that we're on the 'urban frontier'.
As you get closer to Baltimore there are a few abandoned homes on 49th, and I feel that block might suffer for it. However, I think the building of the townhomes at 49th and florence is potentially a positive change.
Let me know if you have any specific questions.