If you get in for free, this is a great attraction. There are coupon books in cabs and what not that have tickets. AAA also gets you in for free, I think. I just read on Yelp that the auto collection website might even have a free offer.
If paying $10 is the only option, I would recommend going if you really like cars. Probably not the best place to take the uninterested wife/girlfriend. The reason for that is that the setting itself isn't all that nice. Have you been to the Imperial Palace? If it were in the Bellagio or Venetian, I probably wouldn't feel the same way.
Anyway, there is a nice collection of classic cars and some are for sale. The museum is pretty large (the whole 5th floor) and there are some famous "Vegas" vehicles on display.