Hi Jin,
My top 5 reasons for investing in Baltimore is:
1) The Accessibility - it is a great central location and short train/bus from major markets in Philadelphia and DC and local markets like Newark/Wilmington DE, Annapolis, Frederick, Silver Spring, Columbia, Hyattsville etc.
2) The University Systems - Top Tier Schools in their respective industries like JHU, JHU Medicine, UMD Law, UMD Medicine, MICA, UMBC, Loyola. Also lots of excellent local schools like Coppin State, Morgan State University, Goucher College. Collectively these school systems produce a lot of rental demand and are appealing to large companies. A multinational eduction company, Laureate International is also based here.
3) Local Industry - The main industries in the area are sometimes referred as "Eds and Meds". Industries like biotech, medtech, and pharmaceutical research will set up in and around Baltimore due to proximity to both JHU, UMD and the National Institute of Health, which has a $30 billion budget, majority of which is distributed as research/project grants. UnderArmour's headquarters are also based in Baltimore.
4) Value - residential properties easily earn 10%-12% year 1 (for those who know the areas best) and the high cap rate is driven by the immense demand for rental housing. This is due to the relatively low purchase price for an urban market as stable as Baltimore and the presence of a large low-middle market population.
5) Stability - contrary to what you read about, Baltimore is very stable. The cap rates have lowered very slowly for a long time now (lowering cap rates means higher property values). Of course the market hasn't grown at the rate of others like DC and the Southwest cities you are hearing about, but it continues to grow for investors which means appreciation benefits over time.
For a long-term investor, Baltimore means high cash flow, stability of a large metro area, equity buildup from paying off mortgage with rental income, and slight appreciation.