Ales,
All property markets go in cycles. If you speculated in Palm Jumeirah in 2005 or earlier and sold in 2008 you would have made milllions of £ like many have done from Dubai.
Currently the property cycle is close to the bottom in Dubai (as it is in most countries now) and a good time to buy in (not to get out). The recovery in Dubai should start to happen in 2010 and Dubai is set to recover faster than others. Prices will rise from then but probably much more steady and slowly from that ponit as the greedy speculators have left the market and Dubai will become a mature market for professional investors.
Stick to stable developments that are in demand such as Dubai Marina where you can now obtain high rental yields on completed properties.