I have been hosting my website on Site5 for the past 5 months and I am really happy for their services. I had some specially requirements for a software, many of other hosting companies did not let me to install by myself, but Site5 did it for me, the staff helped me a lot to configure it for my needs. I really like their servers performance. So they are great for my Hosting needs.

I m a Site5 Customer since 2008, service is awesome and reliable, technical support is always reactive and responsive : they just dont know to say no :)))
I have a reseller account and i has a ZERO down time since 2010, just one problem happened on 2009 and i have received a service credit for that. And just after that come a server hardware update then the hole server was changed ( so happy :p )
I also noticed that by the arrival of Ben as the new company CEO, many things changed : company strategies and service was going more greatfull : SiteAdmin update, Backstage update, Hardware Update ... i realy love the every three month Site5 State, this let customers know what they are doing and just feel as they are a member of the family.
I recommend their hosting service to every one ( they are offering a free month trial account for shared/reseller/VPS so enjoy it )

Site5 is an excellent host. I've been with them for a number of years now and have had nothing but an excellent experience. Their customer support is insanely fast & helpful. I've recommended them to many people over my time at Site5 and I've never heard a complaint back.

Site5 are a good choice. I use their shared hosting service for quite a lot of time, hosing a Ruby on Rails web application with a MySQL database.
Having a secure shell access and complete control over the DB and local files, makes it feel almost like using a powerful VPS.
But there are some cons too. The performance of the site is sometimes poor (very slow response). I think it's mainly due to the high load on the shared server. They also had some other technical glitches mainly after server upgrades that broke my web system. But at least their technical support guys fixed the problems quite fast...