I only used MtGox once.
I deposited 10.00 BTC, sold it, bought it back a little cheaper and tried to withdraw, but it told me I couldn't withdraw because of some problem with PayPal. I never used PayPal with MtGox; I don't think they even support it. I reported it to them and they ignored me. I think the problem may have been that my USD balance was -$0.01 after I tried to spend all my USD for BTC. So I sold the bitcoins again and bought them back a little cheaper again. This time my USD balance was $0.00 and I was able to withdraw my 10.17 BTC. So I made a 17 bitcent profit, realised I had been risking considerably more than I gained, and decided to stop messing about. My closing balances were $0,00 and 0,00 BTC.
Then the hack happened, and I went through the 'reclaim my account' process just to see how it worked.
When I got back in, I had $0.002 and 0.008 BTC. I used to have nothing.
It's not enough to worry about, but it makes me think that something is wrong, and if they can get my zero balances a little bit wrong I'm sure they can get other people's balances much more wrong.
I like https://britcoin.co.uk/
- it's commission free, and allows free bank transfers in and out (for UK banks).