Boston is a great place to live.
My knowledge is a few years out of date, but for what it's worth:
If you live in the Boston/Cambridge area, a car is a liability, not an asset. Boston and Cambridge are a maze of one-way streets, dead ends, poor signage, and crazy drivers (they don't call them Massholes for nothing). You have to find somewhere to park your car, and that can be challenging, expensive, or both. And with the T, you really don't need a car. If you need a car once in a while to go to Costco or something, rent one for the day, or get a Zipcar (I believe they were founded in Boston).
Finding an apartment wasn't easy when I was looking for one (1997), but that may have changed. It's not wrong to start looking now, especially if you want to find a roommate as well.
The city is generally safe, as long as you use your common sense and don't do anything stupid.
The bar scene is pretty good. I can recommend a few places.
Keep in mind, though, that the bars close at 2am and the T stops running at 1am (unless that's changed in the last couple of years?), so if you're going somewhere not in walking distance, either take a car and have a designated driver, or be prepared to wait a loooong time for a taxi. (Or, I suppose you *could* leave the bar by 12:30 or so... nah
)
*sigh* I miss Boston...