In the beginning:

For years it was like this. When I had a problem they were prompt in fixing it and everything was great. At one point my entire site disappeared for no apparent reason and they were able to recover the entire thing. It had been an error on their end, anyway, which they readily acknowledged. Again, great.
But then, downtime:
When my WordPress installation began including JetPack, which now includes site monitoring, I began to notice a problem. Not with WP or JP, but with HostGator and site uptime--I hadn't been closely monitoring it before this, though my site seemed to be up most of the time. I was constantly getting emails from JetPack informing me my site was down. It happened so much, it became unbearably annoying (especially since JetPack also emails when the site is back up). I wasn't getting anywhere near the 99.9% uptime they were promising. Considering I was paying about $11 per month, I wasn't happy that I they weren't holding up their end of the bargain.
When contacted about this they try to blame everything but their system. If you're running WordPress they'll blame your plug-ins, even though they've never been a problem before. Their unwillingness to take responsibility for their system's failures is not only frustrating, it's dishonest.
Billing:
At first my hosting was less than $5 to host one site. Then I upgraded to unlimited hosting for about $8.95 per month. Over time the cost has slowly crept up. They notified me by email that they would begin charging me tax, then wanted me to cancel my PayPal subscription and re-subscribe for the new amount which is a pain in the neck.
Suddenly, it was no longer passive and easy. It became something I had to worry about, because after this their billing went down the tubes. On several occasions they billed me twice in a month, on others they said they couldn't process my billing even though nothing had changed with my billing information. In the several years since the cost went up it hasn't ever gone back to being simple.
Customer Service:
This is my number one problem with HostGator. Their customer service was amazing. They connected fast, stayed on the line until your issue was resolved, were pleasant, spoke clearly, got back to you fast, and seemed knowledgeable. All areas of their chat support were like this. Billing and technical support especially so. This is what I loved most about them.
Sometime over the last six years, though, their customer service has tanked. It often takes 15 minutes to be connected with a rude person who can't actually resolve your issue--they just want to get rid of you so they can move on to the next person in the queue. This problem becomes much worse when you try to cancel. So, the issue you contacted them about doesn't get resolved and you've just wasted 20 minutes talking to them about it.
The bottom line, their customer service is terrible.
Finally, cancellation:
Remember way back when AOL was a thing and trying to cancel them was almost impossible? That's what it has been like for me trying to cancel with HostGator. Apparently, the only way to cancel is to fill out a form. I filled it out, twice, but got no confirmation and today they tried to bill me for hosting. When I contacted billing they very rudely told me to fill out the form (again, I had done so twice before) and then disconnected our chat while I was still typing. Since I can see when they're typing, I know they can see me doing likewise.
Per their instructions I tried to fill out the form again, but like before I kept being kicked out of the system. I tried it twice more, still kicked. Then I tried it with Internet Explorer which worked. This really ticked me off. First, what kind of internet hosting business isn't compatible with Chrome? Next, if their customer service/billing chat support had spent just a little more time trying to resolve my issue and find out why I had filled the form out twice and it hadn't worked, I wouldn't have wasted so much time trying again (which is what he told me to do). The only advice he gave me was to clear my internet cache.
If their system isn't compatible with Chrome, this is something their support people should tell customers who're having trouble with their system and forms. But, they didn't which caused me to waste my time.
The bottom line:
There was a time when I would have, and did, emphatically suggest HostGator to every person who would listen. They had great support and their system was user-friendly. But, I cannot suggest them anymore. In fact, I suggest that if you're looking for hosting you look into the sites suggested by WordPress. Avoid HostGator, who brings in customers by offering them good deals. In my opinion and though my experience, however, no deal is good enough to make up for the bad experience you'll have after you've signed up.