I have been using a VPS for about a year and half now I registered with UltimaHosts on the 15/11/2009 so I have a fairly long history with them. I was previously with another company based in the states that was slightly cheaper than UltimaHosts but not by anything noticeable I left them after they accidently deleted one of my VPS's and left the broken one unfixed. So I moved to UltimaHosts a little skeptical after having a bad experience and since being with them I have been very impressed.
Every now and then computers have problems we all know that, Ultimahosts has never gone below the 99.9% on my Virtuozzo VPS. They once went down for a few hours but worked hard to resolve the problem and thats once in the over a year been with them. The only other problem I had was there was a problem with there billing system so I was unable to pay them straight away(you can see why I worried about this problem), but this one resolved smoothly and has been running ever since without Issue.
There are always three measures when it comes to hosting in my experience one is performance, this has never been a problem with UltimaHosts the connection from the German vps to the UK is wonderful and the server performs well under load. The second is uptime that as I said before is excellent. Then finally its rapid support that we all hope should be needed because of the excellent uptime, well having raised a handful of tickets over the last year I with rapid response to memory (it has been a while since my last one) problems are certainly resolved in 24 hours if not just a few(2-5).
Finally I have to admit there is a little of persuasion in this article since they gave me an offer no one in the computer industry could refuse review our Google Checkout and get a free budget VPS. So everything I said above is true and unbiased since I wasn't even asked to review them but It has been a while I feel I know them well and can give a good opinion of UltimaHosts.
So heres a bit of info on Google Checkout,

Firstly as always start with bill, nasty as it is to deal with bills it is very reasonable price from UltimaHosts

In my case I had already signed up with a Google GMail account, so was straight through to the card details

Standard security check my login details

Finally confirm purchase

We're all done money whizzing its way to UltimaHosts

All done and bill is paid
Well how simple is that enter a few details credit card etc, and payment done. Very fast very easy and would recommend google checkout to anyone.