Hello everyone!
I figured that I should be the one to inaugurate this subforum and I will do so by reviewing my own hosting provider.
On the 6th of January 2005 was the first anniversary of my sites being hosted by Hostgator. One of those two sites is
http://whreviews.com . This forum is hosted there as well, so in all I now have three sites hosted by Hostgator.
How it all started: my sites used to be hosted by another hosting company that had a fair reputation on the various hosting forums out there. My own experience with that host wasn't good though. Bottom line is that I failed to heed the early warning signs I received and kept on using them for far too long. To this day, problems with them are still regularly surfacing at WHT.
On the 29th of December 2003 (or was it 30th?) I noticed that the server of my old host was down. One thing led to another (New Year's party in between), my sites were still down 6 days later, even though I was promised multiple times that they will be taken care of.
At that point in time I decided that it was enough. Besides, it was funny (in a not so happy way) to have a site that recommends good hosts, down for so long. Note that I wasn't recommending that host on my site, so the visitors were not mislead. In case anyone is very good at math and wonders where two days are gone from the story, they are the nameservers propagation days.
So, why did I choose Hostgator? Because out of the 13 hosts on my list of Honest Hosts at the time, Hostgator's owner was the (only) one who was truly cooperative when I let him know that his company was listed on my site and he unexpectedly supported my site (whreviews.com) at a time when it was just starting and it was quite far from being the resource it is now.
Moving my sites over to Hostgator was as easy as it can be. The accounts were created, I uploaded the content, changed the nameservers, and waited. Oh... I did have backups. My sites were static in nature so everything they contained was on my hard drive as well, for editing purposes. Always have a backup! Or be prepared to face the consequences...
Back to the review: In the first few months I didn't use a service to monitor uptime, but between me keeping a close watch on it and checking my emails every 10 minutes, I doubt that any noticeable downtime took place. While I was awake that is.

After some 4 months with them I learned that they will switch datacenters, going from NAC to ThePlanet, in a move that was aimed to ensure the continuation of quality services being rendered to customers. (One of their providers was pulling servers from NAC to their own fully owned datacenter and this would've meant some downtime.)
The whole NAC->ThePlanet moving process was spread over a few weeks (if not over a month) so that things could be addressed properly and the move made as seemless as possible. The old servers at NAC were kept online for a while (a month or so) so that the customers could get any info they needed out of them. I did make use of that to check on any emails that might have remained there.

The move of the server I was on, was as smooth as possible, meaning that no noticeable downtime occured. One thing that did happen was that I had to set things again so that .htm files would be parsed as PHP, but that was it. Unfortunately this meant that for a few hours my site's navigational panel was missing.
That was roughly the time when I decided to test siteuptime.com's free service and what better way than to have it check on my site's uptime?

Siteuptime's service seemed good initially and the first downtime I've witnessed with Hostgator was brought to my knowledge by it. After the obvious enquiries that followed, I found that a DOS attack was causing interruptions of service.
In the last few months it happened much too often that I received notices of downtime from either siteuptime.com or host-tracker.com while I was online and I got to verify my site, and the alarms proved to be false. A fortunate thing for Hostgator's image, but unfortunate for me because I started to lose confidence in these monitoring services.
Another downtime that I remember took place when they upgraded the kernel on the server. Now that's the kind of downtime that you can only happily agree to because it is for your site's good and there's no way around it: the server must be rebooted. Luckily this only takes minutes.
There were other short downtimes reported by the services noted above, but in all, I would say that the uptime must have met or been very close to their uptime guarantee.
I only contacted support when I needed explanations regarding downtime. I contacted the live support by IM (using MSN) and even though the responses were not always immediate, they did come in a timely manner.
A thing that must be noted is that their live support (live chat and IM) is level 1 and handles the simple requests. For things of a more serious nature a support ticket must be opened. I never had to do that and this is a testament that nothing serious ever happened to my sites while I had them in their care.
That's it. I hope you found my review informative.
Thank you for reading it.