Since I've been a customer, uptime has been reasonably good, with only a few (very) short outages that were rectified quickly.
You pretty much have total control over your domains. You can host both the domains and websites here at DreamHost, or you can host the domains elsewhere and point them to DreamHosts DNS servers. I believe the 'unlimited' applies to both situations.
The major annoyance I have with DreamHost is the Web Admin Panel. They do not use cPanel, preferring to use their own homegrown panel. While their panel is fairly complete and offers most of the functionality that you could want, it is also extremely slow on occasions. This has been especially the case since the recent plan changes (and influx of new users).
Many users have also reported a dramatic slowdown in their websites recently, possibly also due to the recent influx. Personally, I have not noticed a speed problem with my sites, just the aformentioned Web admin panel.
Hopefully these problems are a temporary symptom and DreamHost will take steps to rectify the situation soon.
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