Pretty much a dump. Not a great location, rooms are small and guaranteed to smell bad. The whole place wreaks of smoke even if you're in the no-smoking section. It smells truly awful, I can't emphasize that enough.
As I said the rooms are small, the windows don't really open. The beds are far from comfortable, though not painful like some other hotels I've been at. There was a small low quality tv in the room and the bathroom was a pretty tight fit as well. Thankfully I minimized my time spent in the room.
There may have been a gym somewhere. Excalibur has a pretty confusing layout actually despite seemingly being a square. There's plenty of gambling though and cheap gambling - $5 and $10 tables were pretty frequently available. The downside though is that it's pretty far from the rest of the strip; I much prefer to spend time around Caesars, Bellagio, Cosmo, Aria. And there are cheap casinos there as well (Quad, Harrahs, etc).
There's just one thing going for Excalibur - it's cheap. I think I was paying between 30-60 per night. Pretty tough to find that price anywhere else on the strip. But you get what you pay for...not much.