Everything Stablehost has can be considered good.
It's not just a shared host, though they're best known for it. It has upgrade paths and they are not a "me too" type of host (meaning some hosts offer things they're not any good at).
When you're already with them, you can stay with them.
They're not on the VPS only lists not because they're bad, but because there are slightly better hosts -- usually hosts that only offer VPS as they specialize in it. Possibly cheaper, too. (But don't decide on a host based on price.) But they didn't offer shared, semi-dedicated, reseller, etc. If I were already at Stablehost, and liked it, I would not move.
In fact ... we didn't!
This site uses a Stablehost VPS, in the group of servers that runs it. That should say something.
They offer non-oversold OpenVZ plans (UBC/burst). While OpenVZ UBC is historically not very good, and can be overloaded by hosts quite easily, Stablehost doesn't do that. That's one reason their VPS are higher priced than others (Virtuozzo and OpenVZ hosts). Though I wish they used vswap instead of UBC, I have no complaints for 18+ months now of using the VPS.
They've been one of our main hosts for 4+ years now. We wouldn't stay if they weren't really, really good!
