Amazon is widely known as having the most customer-friendly return policy of all the major ebook retailers, but that could change soon in Germany. New regulations will be going in to affect in June 2014 which will require online retailers to offer refunds for ebooks and other digital downloads.
Starting 13 June Germany is going to extend the "right of withdrawal", the legally mandated return policy, to include digital purchases. German consumers will be able to request a refund for any reason in the first 14 days after buying an ebook, and the ebookstore will be required to grant it - with exceptions.
The new regulations could prove to be a boon to consumers, but they come with a loophole. Retailers have the option of trying to get consumers to waive their right to a refund. It's not clear to me whether the ebookstores will update their terms of service with new language that excludes returns, or if they will have a check box and/or boilerplate in the check out process, but it does look like the new regulations won't be quite as useful as one would hope.
Europe as a whole has much better consumer protection laws than the US, but this is the first that I have read about the laws being extended to include digital content. Alas, the laws don't extend nearly as far as I would have liked.
On a related note, the regulations going in to effect are intended to harmonize German laws with EU directives on consumer rights. This is intended to create uniform laws across the European Union, but I can't find reports that similar regulations are being enacted elsewhere. This is a topic worth keeping an eye on, IMO.