I was on 300mg of Effexor PLUS 20 mg of Lexapro. Didn't feel much better, but the addition of Lexapro started changing the way I think. I started making desperate choices, rather dumb ones, and my wife saw it, I saw it, and it took me about 3-4 weeks to get off the stuff.
By the way, Rock Lobster, those strange feelings you experienced are called "Brain shivers" and I was having them even on a daily dose. Those would be the last effects I felt on that stuff.
I have been off the stuff for about 4 months and I noticed little difference on my happy meter.