I was pleasantly surprised with Top of the World. I didn't have high expectations because it was located in the Stratosphere, which admittedly isn't my favorite. We decided to give it go after seeing an online deal come up for it and I'm glad we did.
The ambience is nice; the view of Las Vegas from the restaurant, as I'm sure goes without saying, is amazing. The service was also really great; our waiter was polite and attentive. We had a drink at the lounge upstairs while we waited for our table (the wait was much longer than they told us, but we were a no reservation walk-in, so no big deal).
The food: We started with the Lobster Bisque, which was really, really good. The bread they brought out was served with a very inters testing orange ginger butter that we both really enjoyed. My girlfriend had the rack of lamb and I had the New York steak; both were of great quality, were cooked perfectly and tasted delicious. I will say that the food feels a little dated here; that isn't to say that it wasn't executed amazingly, because it was, but it felt a little less current than I might have expected and I think that some other reviewers might be giving it less credit because of that.
It was well worth the price and I'm glad I finally made it there. The added bonus was that we were able to go to the observation deck (and to the rides) without paying the tower ticket ($12-$16 each).