I dislike Namecheap for a few reasons. They don't let you log in with a _valid_ username and password if you are using a VPN. Their UI is pretty bad, too. If you have an adblocker, you don't see "Submit" buttons on a lot of forms (editing WHOIS information, etc.)... lots of small annoyances with their service.
My main gripe is that I wish they would include free SSL and they give their UI some love but that's minor as I only access it on certain occasions.