I have worked hotels and the majority of issues I have had with bookings are ones that come through them (BDC).
Lack of ability to put the full information on, because they want the commission and they know there's people who want to book quickly and effortlessly, unfortunately although you can do this as a customer, their platform and system doesn't make it that easy on the other side to make sure everything is as it should be, plus the fact that people don't read what they're booking a lot of the time either. It's usually the property that get the blame and the crap for it in either scenario, when the issue is either user error or the way BDC works.
BDC are hit and miss to deal with from the other side as well, they take ages to respond to messages and although they do answer the phone, they always have to ring you back as they can't deal with the issue, usually when you've got a raging guest where something has gone wrong and you need to speak to them to establish what has happened, which of course pisses them off even more.
People don't read messages a lot of the time either, I've experienced more than once had people book and the booking is cancelled, by BDC 48 or sometimes 24 hours before because there's been an issue with BDC taking payment. The guest has had a message to tell them that the payment hasn't gone through and the booking is cancelled, but don't read it and still arrive, which then leads to all sorts of problems - obviously the biggest one is if the room has resold in the meantime! One place we had to monitor cancellations and ring those ones, which we shouldn't have had to do because a) the guest should read their messages and b) BDC should be doing the monitoring when they're charging commissions for the bookings that come through them.
Every place would send an auto message to every guest but they inevitably turn up thinking they've booked one thing, not bothered to read their confirmation, or the messages sent automatically, or indeed what they're booking in the first place and then there's hell on.
BDC is great for guests on the face of it, but it's not so great for the properties sometimes and of course that leads to it not being great for the guest - but usually the property gets the blame!