I've been with RezellerZoom for four months, since Dec 2004.
The initial setup went very well without any kind of problems what so ever. My account was created under 24 hours, and the sing up email was clear, precise, with good information and very polite.
Their servers are reliable and fast. Although this last month they ran into some problems, they managed everything in a very good manner and did their absolute best to minimize the downtime. In the last three months the uptime was above 99.80%
What really makes them great, in my opinion, is their support. I had a few questions during these 4 months and every time I submitted a support ticket it was answered in less then 20 minutes in a clear and helpful manner. They strive to help each and every user no matter what problem arises. The support is really great and it's trully 24/7.
They are great budget reseller, and I am very happy and pleased with them, and I would recommend them to anyone. The site I am hosting with them is my evil hosting
project. I will also keep track of their performance and be back with an update in a few months.