Familiarity:
I have been a loyal customer of MidPhase since early 2003 - I'm pretty sure that I am one of the oldest. I originally signed up with a company called Thrillhost - which MidPhase later acquired a year or two later. Because of this my hosting package is a tad bit different than the standard - but I am hosted on the same servers and deal with the same support. I have spoken with the the past two owners of Thrillhost and Midphase and I believe their friendliness trickles down the company.

Flexible:
As a web developer, I use my hosting account to develop web applications, primarily with PHP and MySQL on this account. I could not be happier with these services; both are just as fast as they should be. I have a few database tables with 50,000 records and queries are executed very fast. MidPhase does a great job keeping the software up-to-date and the hardware up to present standards. I have come to some projects where I need a PHP extension installed (ex. PDflib, Ming) and as long as it is a stable product MidPhase seems to help out their customers by installing extensions in a timely manner.

Problems:
About once per year MidPhase will change a configuration on the shared server I am on which affects my projects in a negative way. Most recently my account was moved onto another server which did not have extensions I required. One would think that the tech agents would make sure this wouldn't happen - but when you have hundreds of accounts to move I can't say I blame them.

Support:
The largest issue I have with MidPhase is their support. A realistic average waiting time for phone support is about thirty minutes. I've had times where I only waited five minutes, but I have also had my cell phone run out of battery power as well. Support agents speak clear English and are both helpful and friendly. However, if your problem is moderately technical, they often cannot solve your problem. They usually ask for your email and will have somebody email you the next day about the problem.
I have had very little success with their online support chat. Overall MidPhase offers an acceptable level of support, but is not superior by any means.

Summary and Recommendation:
Thrillhost is great for personal and small to medium-sized business websites if and only if you choose a package that offers unlimited MySQL databases.
Some of the key things I look for in a hosting company that MidPhase provides are CPanel, Unlimited email, MySQL, addon & sub domains, FTP, and PHP5 (not 4.3!). Other pluses are Cron jobs and Python.