Depends on the package...I was on shared hosting. Here's my experience with Shared hosting:

At first when they transferred my sites, they "forgot" to restore the databases and none of my sites that relied on that worked. Took me over a day to figure that out on my own (tech support didn't recognize the problem and wasn't helpful).

Then I kept getting outage notices from my monitoring service.

Then they changed to phpsuexec and didn't tell anybody which meant re-working every .htaccess as well as the php.ini for each site (and I had at least 20 of them). Getting an example php.ini from them was like pulling teeth. I finally posted that to the forums here for anyone else who may have been having problems with 500 Internal Server Errors. Some people who had this happen to them had their sites down for over 36 hours and no word from tech support. It wasn't until I posted to the APTHost forums that one guy, in particular, was very grateful for my post otherwise he never would have known.

Then, I kept getting "Server Busy" errors, even on tiny little straight html sites. They claim this happens when a person exceeds their CPU usage. Well, they must have had my accounts set to 1% instead of 10%. The final straw was when I was only updating the front page of one of my ecommerce sites and got the "Server Busy Error" in the middle of updating one page, is when I hit the button for Google and started shopping. It wasn't until over 2 weeks later that they finally replied to my support ticket about the issue saying they weren't using cband-status anymore...but it was too late by then, I had already moved on.