Same here, I've never had any issue personally with the service, but they have had some issues in the past (a RNG issue that allowed some accounts to be compromised, and some blockchain sync issues that stopped users from making transactions that didn't have their private keys). I'd trust them, and did with my bitcoin paycheck for years, I'd just suggest you record your keys so you can move your coins should the service go down.

If you don't have sole access to the private key, you don't technically have control over the coin, in my opinion. Something to chew on.