I've been really tempted by the 25 f/1.4 but it is really larger than I'd like for this system.
It is large, but it's a great lens. I use it mostly with the L1 and E-1, but when you need a normal and it's dim out, it's the one to have.
I was interested in how others would use it if they had the G1/GH1 and I can see everyone has a bit different way/reason. I'm still honestly not sure w/o the VF if I would get a lot of use out of it. I'm not a tele shooter (thus less interest in IS)--my 45-200 is rarely on my camera-- I'm not a street shooter--and sometimes critical focus (MF) is very important to me and I'm just not sure about that with only an LCD.
The G1's 'two-button-press to get to focus assist' is much more convenient than the E-P1's 'get to the right info screen, press ok, dial in magnification'. But beyond that, the screen and magnification seem just as easy to use as it is with the G1. The real question is whether you prefer to use a TTL eye-level viewfinder more.
Personally, I see the E-P1 as my two-three lens camera: the 12.5mm, the 17mm, and a 35-40mm will be just right. Wide lenses are easier to use with the LCD than long teles, unless I'm using a tripod (then teles are great!).
I see these two cameras as two complementary bodies with different feature sets and very similar image quality potential. If you find you use the viewfinder a lot with the G1, and prefer it for your critical focus work, I'd say the E-P1 is probably not the right camera for you. I'd wait for the next Olympus before doing it.
There's no need to be in a hurry. Consider your photography and act on that basis.
I saw the Cube with the EP-1 .. LOL
Someday I'll give you all a real laugh and dig up the photo of my ultraminiature Minox IIIS fitted to a 22lb pro tripod and head ... ];-)