I have no problem logging in, and there is quite a lot of trading going on right now so I guess other people don't have problems either.

I'd rather use britcoin than anything else tbh as genjix has been involved in britcoin for a while, seems to be committed to it and although the site is clearly 'beta', it is functional.  Also he is just down the road so if he stole my money I could turn up at his house with a bat...  but no, seriously I'd much rather use an exchange in the same legal jurisdiction as me.