My dealings with Fictionwise have been excellent. Their customer service is slow as molasses, but they always get the problem solved and cheerfully. And I've had a ton of problems. Several books I bought were linked to the wrong book on download. Other books gave me a message that they weren't available. One book had such poor formatting that it was unreadable, essentially one long paragraph. Fictionwise either corrected the problem or refunded my money in every case. You just have to be patient as it might take them a week or so to get back to you.
The slowness of the customer service could be an issue, but they are so much cheaper for books than anyplace else, as long as you massage the system correctly, that it's well worth it to me.