Just saying, if they don't use split key generation then it's highly likely they have a copy of your private key and hence will be able to steal your funds any time they like. My advice is to NOT use this service until they offer split key generation and delete any of the addresses generated by them and not use them. If you want a vanity address the best way is to do it yourself on an offline computer using vanitygen/oclvanitygen.
not everyone got this option to do it by yourself, i can do in reasonable time maybe 4-5 letters max
i will trust them, time will tell if they are honest, people trust blockchain.info with their wallet online, which is also based on trust only