Were people genuinely expecting the 480 to match 980ti?? I thought it was just a bit of forum banter, I didn't think anyone really believed this would happen. Apparently I was wrong! Some people were expecting it to have that level of performance.
The best info we have is from the AMD demo against the 1080. That places the performance somewhere around 980 levels. It would take a massive overclock to reach 980ti/1070 levels of performance.
If the 480 cards do offer 980 performance levels and are decent overclockers at a sub £250 price, then, they will be very good cards. Certainly they will be tempting to people on older cards like the R9 290's. Well, I will definitely be considering the switch.
On the other hand if they only come in at 970 performance levels, that will be a little disappointing.