I've had a dedicated server with managemybox for one month now and overall I have been satisfied with the server. I signed up for the special and am paying $59/month for an athlon xp 2000+. There were a couple of setbacks in the beginning - the file system got messed up somehow (very well could have been my fault - I'm not sure and I have very limited managing skills) but they had it fixed the morning after I sent in a request for service. I had another issue with the PLESK mail server (not sure if they did not configure it correctly or if I messed it up) but they were prompt with responses and fixed it quickly.
Overall I'm very satisfied with the value I'm getting from the webhosting, every request I've had has been satisfied in a timely manner.