I've read that they will substitute titles if they can't get what you are looking for. That hasn't happened to me, but it was recommended that you specifically request no substitutions.
Also, since I don't know where you live, I should mention that many of their titles are Region Coded. Therefore, if you are in the US and own a multi-format DVD player, you better make sure that it is also a multi-region DVD player
Do a search for them in this forum. I learned about them here from a few reviews.

