I talked to Ruben at a printing information market at our university. He was very helpful and explained the printing process and what Gildeprint had to offer. I received a quote very quickly and it was no problem to make changes to the order once I had finished my thesis completely (it had a slightly different number of pages than I originally thought, and I changed my mind a few times about wanting some hardcover copies). The company responds very quickly to emails and you can always phone them.
Once I emailed my thesis, they printed a proof copy. I could then make some final changes. This took me a week rather than the usual 2 days but that was fine. After I sent the final corrected version, it took around 6 days for my thesis copies to arrive.
Unfortunately, the colours were not good. Compared to the proof, everything looked very grey to the extent that some figures were unclear. I emailed Gildeprint about this, and Ruben phoned me within 5 minutes to discuss it. He suggested I send them a copy of the "grey" thesis together with some pages from the proof for comparison, then they would look into it. I got an email a few days later saying they had received it, and then nothing for a few days. Then they called, saying they didn't really know why there was a difference. Initially they offered a small financial compensation, but after we talked some more they realised that the lack of bright colours was a major issue for me. Eventually they decided to reprint.
I just received the reprinted copies and they are beautiful, with the same clear colours as in the proof. So all in all I am very happy!