I used to come here before I discovered ISBN numbers and Bigwords.com. Like most incoming freshmen I got ripped off plenty of times by the University Bookstore. Paying $100+ for a English or Biology book only to be offered $30 at the end of the semester for "buyback" sucked. Fortunately most students have come to learn that you can just copy down the ISBN and buy it for pennies on the dollar online.
While this can be said pretty much about any of the textbook stores that service UNLV, the on-campus bookstore does have a few perks that set it apart. This bookstore is the only one that offers supplemental packets you need for some of your classes. The packets are printed on campus and only sold here. You can't get them at Rebelbooks and thankfully they are usually inexpensive. The store also has a ton of UNLV swag and a portion of their sales are donated back to the university. Expect long lines and tons of people during the beginning of the semester.
Overall its a notch better than the other bookstores but you are still much better off buying online.