I am a student at San Antonio.
There is a cafeteria on the first floor of the dental school. Always busy during lunch hour. There is also a Subway, Freshens smoothie shop, and a grab 'n go thing on campus by the library. There is also a hospital cafeteria at Methodist across the street that a lot people go to as well. Chick-fil-a, Wendy's, McDonald's Starbucks, Whataburger, Taco Cabana, and some chinese restaurants are all really close to campus, and some within walking distance.
The electronic textbooks are not a huge problem if you like to read from textbooks. Almost all the classes have hard-copy manuals that break down what you really need to know without reading an entire textbook that goes into way more detail than you would ever be expected to know for an exam or boards. The only time I read from the textbooks is when there is something I need clarification on, and so the search feature in the textbooks is great. You don't have to spend forever trying to find what you were looking for in the first place. The only textbook I have bought for myself is our fixed prosthodontics course because it is the one course I have had in dental school that has a had a hard-copy manual and additional required reading assignments. You have to do them or you won't do well on the exams.
As far as rankings are concerned, dental schools are no longer ranked. The last time they were ranked though, by U.S. News and World Report (I believe) San Antonio was #1 and Baylor was #13. These rankings really didn't mean anything because it was so subjective anyways, and it was dependent on what information the school submitted to the report. For research though, UTHSCSA is one of the best/highest ranking in the country as far as grants/funding are concerned. So if you ever want to do research while you are dental school, you will have ample opportunity to do so.
As far as things to do in San Antonio, there is much more than the Riverwalk if you have time. If you are in to hiking and camping, Enchanted Rock is about an hour away. If you are in to wine tasting and stuff like that, small-town historic Fredericksburg is about an hour away as well with tons of vineyards out there. Fredericksburg also has a well-known Christmas light tour every year, and you can take carriage rides through town, go to antique shops, etc. Canyon Lake is a short drive, as well as the outlet mall in San Marcos. A lot of people go tubing the rivers in the summer (Guadalupe, Frio, Comal) and there are lots of holiday festivities around the area. In Hondo, Texas which is west of San Antonio, there is a big cornfield maze that they put up for October/November, which is fun to do with the family if you have kids. There are also several colleges in town if you want to watch college sports -- UTSA will be getting football within the next 2 years, and there is always the San Antonio Spurs, even though I am more of a Mavs fan myself. There is tons of live music going on at places like Floore's Country Store, Gruene Hall in San Marcos, etc. The Botanical Gardens had a music fest about a month ago, and one of the coffee shops near the medical center does live jazz every other Friday night. So there is PLENTY to do... when you have the time of course. That's the hard part, finding the time. Oh yeah, and UTHSCSA will be home to a brand-spanking new Spectrum Fitness workout facility ON CAMPUS next spring.
And cost of living is nice and cheap, whether you want to rent an apartment, house, town home, etc.
