I'd suggest reading some of the complaints about their service and support. They have had a whole litany of complaints that span years of operation.
In their defense, I've read that they have improved significantly - but they had a pretty poor reputation to begin with.
While its great to support a company that fights for your rights, it's also prudent to ensure the company meets your service needs.
So, I'd suggest reading sites like WebHostingTalk, and similar. Then, after reading, I'd suggest interacting with them to answer questions and measure things like initial response time. And, of course, basing your judgement on that and not just reviews or willingness to fight for your rights.
I've had various sites on Dreamhost since 2003, I even won their once-vaunted "site of the month" contest in 2005. I've used their shared hosting, VPS, and dedicated servers. I've also hosted plenty of sites elsewhere (Hostgator, Bluehost, etc).
There was a period around 2009-2010 where Dreamhost tech support became bad--aggressively bad. Replies to support requests were very slow, and when they did finally arrive they were terse and unhelpful. I think that period really damaged their reputation. Due to the crappy support I was planning to migrate my sites elsewhere, but it was a big job that was easy to put off.
Around 2011 they must have changed something, because the quality of tech support improved considerably, and they've been a great host since then.
I've had a few servers (and previously shared hosting) at DH over the last 20 years. While they have had their fair share of major downtime, it has been on par with Rackspace, AWS, etc., who have all had day+ events in the last.
I have heard reports of some shared servers being worse than others, but generally I've only seen reasonable performance at a low price.
That said, I also use Digital Ocean, AWS, and Rackspace still for various projects. Really, they're all pretty great.
Most of the complaints I've seen have revolved around their shared hosting environment and some support complaints. I figure it worth mentioning. I do know there are far fewer complaints AND that they are still in business, so they can't be too bad, can they?
But, yeah, at one point their shared hosting services had quite a reputation and they had lots of complaints (reasonable or not) concerning getting terminated for unreasonable resource usage when hosters felt they were in the right.
I had a personal site with them for a few months and had some downtime that put it below my acceptability level. They were pleasant enough to work with and refunded the remainder of my money without any compliant. I don't recall the exact figure but it was in the 95% uptime range.
Caveat emptor, I suppose. Refunding and moving was easy enough. I'm in the market for hosting, again. So, maybe I'll give them another shot.
I've been with them since 2007 and they did have some bad years, and just last year I was getting quite a bit of downtime due to someone attaching the shared server I was on. I asked to be moved to a different server and have had like 99% uptime since. So while there are issues now and then these days, support does help you if you ask. Plus for what I pay, I think it's great value.