Freedom of speech is great - but don't bite the hand that feeds you! I can speak freely now when I'm rid of One.com and it's bad hosting, though. I'm going to try to highlight the positive as well as negative sides of One.com (but mostly negative, since One.com is crap). Today I'm using Swedish host Binero and I'm happy with the result.
Reasons why not to use One.com
One.com was my first web host, so they set the standard for what I thought was acceptable. Downtime two times a week is unacceptable, but how would I know? I've had two sites hosted at One.com and both had issues with downtime. Problem is - One.com won't tell you when they shut your site down for an hour or two. You will, however, receive a notice if there is maintenance about to happen (which could take 5-8 hours to complete).
When this site was hosted at One.com it had to go through five maintenances and I found about ten unreported major downtimes. Moreover I can't remember how many minute-long downtimes I found. Estimated uptime at One.com? 90%? It's hard to estimate since errors are not reported, and 1-2 hour downtimes are hard to find if I'm not online. Do not use One.com if you need your material on the web at all times.
One.com Stability and Speed
A web host must ensure stability and speed since it's the reason why we hire them instead of hosting the site ourselves. This goes hand in hand with downtime since a site cannot both be stable and have downtime. According to Google Webmaster Tools my site was slower than 90% of the web. 90%?!?! On top of that One.com threw more Server Internal Errors than you can imagine! And when things went fine you had to worry about the MySQL server slowing your page down! I've seen queries take 3.5 seconds to complete. Do not use One.com if you plan on using software such as WordPress.
We need to understand that One.com is a very simple web host. This is no excuse for the lack of stability and poor uptime but it explains why you, as a customer, are limited. You have access to a web server with PHP and MySQL functionality, although you can't configure the web server directives or the PHP settings. One.com gives you one MySQL-database and nothing more. You are unable to run asp.net applications and as far as I know SQLite is not supported.
Additional domains are not supported and you have limited domain control. If you want to transfer your domain to another registrar you have to talk to support and cancel your account. They rip you off when it comes to domain pricing, but for a single domain it's not that big of a deal.
The mail servers won't support the standard port for sending mail, and they refuse to use SSL (secure connection) for sending and receiving mail. Credit where it's due - the catcher mail functionality is great. It's not unique but it's the only fancy thing you can enable over there.
There is no such thing as free traffic, and One.com knows that. You are, by agreement, unable to host large files on their servers. Not that this in itself is an issue but they also limit the size of a request to 3MB. This means that a site with a lot of images might get suspended. All it takes is one page, so make sure to check the size! Flash-games and such might easily doom you.
Is One.com worth using?
There is no right and wrong I suppose. One.com gives you something that "works" for most people, but then again most people don't own a web site. If you have a blog for family and friends One.com could satisfy you, but beware of downtime and so on. The only reason to choose One.com is their pricing. If you plan on creating a larger site, go and purchase a better package from a better web host!
Bottom line: Do not use One.com as your web host unless you need a cheap host. Be aware of the stability issues and limitations.