Hey Tommy, I bought one of these only a few weeks ago and have run it it at 4-5 times so far, mostly with a Lowe Alpine or Helly base layer, in temperatures of < 5 degrees (Aberdeenshire). Certainly kept me nice and warm. Today (21-Jan-07) it snowed on our 2 hour run, and I had it as a base layer. Got a bit of the old nip rub, but not too bad. It got a little damp through my crappy Ronhill Vizion, but not uncomfortably so.
In summary, I like it an would certainly buy another (unlike the Ronhill).
Geoff