I've never had a problem getting the first two delivered, either from Amazon or the marketplace.

I've never had anything in the last class turn up at all, so I just ignore that category when I put in an order.

The only time Amazon misdelivered was when I ordered some books about Buddhism from the US, and they sent me some Harry Potter hardbacks instead.

I got to keep the Harry Potter, and they resent the original order without complaining.

I don't think they're a great company or particularly good to work for, but they seem adequately competent as an online retailer, so I wouldn't worry about buying from them if it's something that's not available locally.

Tragically, they're almost always cheaper than my local bookshop, which can get most things delivered next day, but charges a lot for the privilege.