Ordered a book last month from them. Expected arrival date was the 1/1. It's over a week later, and nothing. The label was printed instantly, but it then took 4 days to be delivered to the first processing center, according to tracking information. There have been no further updates, after that. Also contacted the shipping service with the tracking number I was sent, and they emailed back saying that it was an untracked service.
Edit, as of 4/2
Reached out via email to ThriftBooks, to explain what was happening, a couple of days after posting my initial review. The person who responded to me looked into things, couldn't find any further details, and issued a refund within 24 hours. They also stated that were the book to show up, there was no need to pay again.
Then, on January 29th, 29 days after the estimated arrival, the book showed up in my letterbox.
So, great customer service has completely changed my opinions and feelings in regards to everything that's occurred.
4/5, due to slow delivery, poor packaging, and a tracking number for a book sent through an untracked service while I was given a tracking number. Would shop again, and recommend to others, but only if you're not in a hurry.