The problems are:
1. Last gen cards that cost about the same, sometimes less, perform MUCH better.
2. Lack of DX11 content makes "I'll buy this much slower card at every game but 2 in hopes they will come out with some more games that I can play in DX11!" a questionable choice. The performance of the card is so poor compared to ATi's own 4890 that even the boost of DX11 can't help it overcome it's narrow memory bus:
http://www.xbitlabs.com/articles/vid..._12.html#sect1
Note the 4890 beating the 5770, even though the latter is in DX11, and the abysmally low minimum fps of all the DX11 cards.
The similarly priced GTX260 offers similar, often better, performance while giving the buyer CUDA, PhysX, 3D Vision, and AA in games like BatmanAA.