The subject says it all. It’s fine to buy domains from them, but if you want to host your site or app, don’t do it. Everything that is more complex than a “Hello, world!” plain text page will be a trouble sooner or later. Even simple Wordpress with custom permalinks is almost impossible to configure. And if you are lucky, they will Upgrade your account to break it.
To make it worse, the moment it happens, you won’t be able to fix it because a simple change to disable their ugly File Not Found page is reported to take from 30 minutes to 24 hours, but really takes more than 3 days (it is still in progress, so I can’t give you the correct time). Maybe it’s because they are using Microsoft IIS? Probably.
Now check this cute “Page Not Found” message. What a style, don’t you find?
To reiterate, DON’T DO IT. Save your time and nerve cells.