This weekend we shifted our servers to a new location. We have heard great things about SoftLayer and moved with them.
The biggest issue we had with our previous hosting was reliability. It randomly dropped requests. One of the irritating thing was it requiring restart after every code change and we didn't had permissions to do it! But then, it was $6 per month. It would be cruel to expect more than that :)
Moreover, with the kind of traffic growth we had in recent months, we felt it moral obligation to move to a better one!
We hope to provide better services with full control of servers. We are already noticing better speed. Way to go!