The fact it's local (well closer anyway - local for me) may mean some people will leave after their team's match, but then there may be more people there in the first place, so those effects may cancel out. I guess the only way to find out is to try it, which is exactly what they're doing. No surprise that plenty in our RL "community" are having a good old moan about it
The only issue I can see is that even though it's in the best stadium in the world (as far as I'm concerned) there isn't the range of pubs around like there is in Cardiff. There's Mary D's (for the brave), the new Summerbee outside bar, and the bars in the stadium, and that's pretty much it. It's a fair old walk into town. Maybe that'll mean everyone's closer together and there'll be a better atmosphere though, we'll see.