It will perform ~15% better on mining overall. ASICS perform ~500% better than GPUs overall. GPUs have long since become irrelevant in the bitcoin mining world. Even if major manufacturers were to add a specific SHA256 function to GPUs, the fact that the only thing ASICS do is SHA256 means that GPUs will never be relevant in the bitcoin mining world again. GPUs are, afterall, basically designed for graphics...
For bitcoin mining. In litecoin mining they are still great and make much more profit.
and the Hawaii will be even more usefull for scrypt jane (YACoin, YBCoin, ZCCoin, J-Coin, Copperbars, etc.) hashing because it has 4 GB RAM, which means its a smaller hashrate drop with every N factor change than the cards with less memory and CPUs. I will definitely get one.