My wife and I visited Burj Kalifa in late March, 2012. It is an ultra-modern building (next a shopping mall that is supposed to be the biggest in the world with about 1,200 stores) that is supposed to be the highest structure ever built. You can take the elevator to the 124th floor, where the view (on a clear day) would be no doubt magnificient. When we visited, a small sand-storm was going on, so the view was not that great but still very impressive.
It costs 100 Dirhams (about $27) to go up, but don't expect to be able to buy a ticket the day you visit. (We bought our tickets a week ahead.)
When we bought our tickets, the agent talked us into buying tickets for two "telescopes" which were really binoculars to see the area better. The cost was 25 Dirham each, which was not all that much, but what he did not tell us was that the tickets could be used on only two binoculars for 21/2 minutes each, and once you started to use them, you had to use up the entire 21/2 minutes on the same machine. So my advice is that you should take your own binoculars and don't fall for the sales talk. All in all, though, it'is a worth-while visit if you can get tickets for it.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC