I've never lived in Worcester, but I live about 40 miles east and have for a while. Worcester is fairly blue-collar I'd say. You don't have the technology and collegiate scene as much as Boston/Cambridge. Parts of it are fairly rough. For a mid-sized city it has most everything though. A mall, stores, some restaurants. Every year some decent concerts come through the DCU Center. If you've got a family there are actually some very nice suburban areas around there. Housing prices are less than inside the 495 corridor, but if you're not familiar with New England they're still inflated.
I've been living in Worcester for a few months now and I'll give it to you straight: it sucks. That being said, it's not the worst place you could be living by a long shot. I live near the medical school (Grafton Hill area), and it's quite crowded. There have been two hit and run traffic accidents on my street in the last 8 weeks, but no violent crime (although Worcester itself has 1.5x the national average for violent crime). My recommendation: live in SHREWSBURY (just across the lake from UMASS), much nicer area. Or, you could live on the West side of Worcester (in the Holy Cross area) which is nicer as well. On the plus side, the rent is a lot cheaper than what you would find in Boston.
As for the program, I don't know a whole lot. However I went to anesthesia grand rounds once and everyone there seemed highly professional. UMASS itself is a huge hospital so I'd imagine there will be plenty of opportunities.