I'm not speaking from the perspective of whether they are accessing user funds or not. I'm referring to the fact that they promised in December or January IIRC that they'll be supporting SegWit soon but until now, we haven't seen anything instead, we're seeing updates for ETH, BCH and there built in exchange.
They seem to be moving towards the idea of a hosted wallet more and more instead of having you control your own private keys with all of this built in exchange crap. I honestly don't even want to see that. If I want to exchange my money, I'll do so with an external exchange just as easily, like Shapeshift.
It's a good feature to have, but it's unnecessary.
All the while they have promised Segwit as you said last year, and still haven't rolled it out to this day. Plus the fact that there is often confusion as to how to operate the wallet due to bugs and stuff, I wouldn't use them. But it doesn't really make them less trustworthy, I just wouldn't use them.