ID basically said it all. It's a pretty good location--not fabulously close to everything like Parrish or Wharton, but certainly not too far from anything, and unlike Mertz and the New Dorms, you don't need to walk up a steep hill to get to class.
In terms of reputation, Dana is the "good twin" (as opposed to Hallowell, a smoking dorm). It has a reputation as being more laid-back than the most social dorms, but certainly isn't always quiet. It has a great location, so it would be much more popular in the lottery if not for the poor design. The combination of mazelike hallways, poor lighting and cement-block walls make some people think it feels dreary. But it's actually not bad. Most of the Dana-ites I knew last year were pretty happy with it.
Freshman rooms are standard doubles, decent-sized. 3rd floor is women's housing, 2nd floor has gender-neutral rooms (but gendered bathrooms). You might occasionally run into a Danabug (little white caterpillar-esque things), more of them on the lower floors.
Dana is great freshman housing! You really have nothing to worry about.