OK you gotta go into this with the right frame of mind.  Sure it's in Circus Circus so just based on that fact alone, don't be expecting the worlds greatest theme park.  Have a few beers (or take some medicinal 420) and you'll be more in the right frame of mind.  The ride that I did when I was there recently with my friend Jennifer were the one that drops you and raises you up really fast (that was fun, but short) [see pic].  We also heard the roller coaster was pretty cool although we didn't have enough time to do it.  All in all there's a few fun rides and it's indoors so if it's too hot or cold to be outside, check it out!