I've had a few deds now, but ServerTweak is my first WestCoast(sadly NorCal) host. My overall experience with them after the first month has been positive.
I picked up one of their AMD Promos, and setup was AMAZINGLY fast! I work graveyard for a dotCom in SoCal and got stuck with the christmas shift.. I inquired about a server at 2am on the 24th.....and got a response within minutes. Never the less after working out some minor details and getting the invoice price right, I had a server the same day! Needless to say at that point I was very impressed.
Some hardware glitches and custom software I have to run fouled up the mix due to some kernel issues with Centos4.4, Ivan and Steven were very helpful and suffered thru two additional rebuilds to get things squared away. There was some lack of communication regarding hourly rates and doing the work before commiting, but in the end it was all sorted.
The network is great, fantastic speeds from all my users(who are spread all over the US and a few outside). Support is fantastic, with only a minor exception as far as billing goes..we are still working on getting the PayPal subscription amount correct, but I'm confident Ivan will get it sorted.....after all he wants to get paid!
If I were to rate my experience with ServerTweak so far it would be a 9/10. And I am actually considdering the co-location of a few servers with them in the next few months.