As others have mentioned:
1) There is indeed a noticeable amount more legroom
2) You'll get a snackbox in the afternoon and evening, and a pasty/danish/cookie in the morning. Worth mentioning that, while these are sometimes passed out (especially the snackboxes), they're more often available at the counter at the end of each business class car.
3) You'll get a soft drink, juice, or wine/beer in business class. These are usually passed out, though I've often seen water and juice out on the counter for taking. You mention the drink being from the snack bar - if you mean the downstairs cafe, it's not from there - you get it from a more limited selection in your own car.
4) There's a coffee urn/dispenser, and basic coffee stuff available for free in each business car.
5) The biggest benefit (at least in my opinion) is that the business cars are often far less busy/crowded. It's *very* rare to see the business cars more than half full, and I've never had to sit next to anyone, over many trips. While this may sound a bit snotty of me to say - it can make for a much nicer ride. I frequently ride from Santa Barbara, for instance, and the coach cars get way more congestion/traffic/activity from UCSB students, which can make it a bit less than peaceful. Again, I don't intend to say this judgementally - merely what some people prefer/avoid.
