Their communication throughout the recent suspension of BTC withdrawals hasn't been the best, but I still consider them a pretty good service provider.
The up and coming new exchange Kraken.com looks very impressive. I've only been using it for about a week but their sites seems more professional than average, with two-factor auth, GPG-encrypted emails, and sensible and proportionate account verification steps. They also did not need to suspend their withdrawals which suggests that their wallet implementation is superior to what both MtGox and Bitstamp had prior to this week.
The major downside of Kraken is that their volume is still tiny.
I have also heard reports that they don't give clear indications of which territories they are allowed to trade with, so some people have signed up only to find they are not allowed to actually use the service, because of the country they live in.
I am from UK and have had no such issues. It is a shame that Kraken can't inform people up-front about that though.