Probably inevitably a lot of posts on a forum like this are complaints from customers who've had problems, so I thought I'd take a moment to take a more positive note. I've been a DreamHost customer for about 4 years, and have seen my share of glitches--mostly server downtime, though much less often in recent months. So I know DH isn't perfect.
Recently my wife reported that a bunch of her DH-based email had gone missing, things saved to the old-messges file. I poked around a bit via logging in to her shell account and discovered some very odd-looking duplication of Maildir folder names that was no doubt behind the problem, but I had no idea how to fix things without the chance of mucking up indexes and data. So I sent a ticket to DH support.
Support responded within the day, went right to the source of the problem, cleaned up the files, and now my wife reports everything is okay.
Considering we're on a $9.95/month plan, that's a level of service I consider admirable.