My 2 cents...
I got my car loan - about $18K from People First. Entirely an online transaction with a good finance rate (at the time). I received a check in advance that was allowed up to the $18K that I asked for - anything under that amount was fine.
It went perfectly. No problems, no issues, nothing. I paid the loan off in advance - no penalty.
My wife, hanging over my shoulder, who worked as a loan originator for several years, (until recently) says: The online loan companies are not inherently bad. There could be a delay in closing or problems with any transaction through an online bank, a mortgage broker, or a regular bank. Your insurance company can hold up closing, the title company could drop the ball. There are dozens of reasons why your loan process could suck. None of which have to do with the transaction originating online.
It is really buyer beware, and I would look for company feedback from other people online who have used them and not just ask randomly of people who haven't used their service.