Before you bought the E-P1, did you do any comparisons with the Panasonic GH1 (another micro 4/3rds camera)?
Lisa
I have both the E-P1 and the G1, and they are very different cameras. The G1 is more capable as a still camera, IMHO, functioning like a very small, compact DSLR. It has fast autofocus, a viewfinder, and a twistable LCD. The E-P1 has a very slow autofocus - one reputable reviewer claims it is one of the slowest on the market. Is is *visibly* slow -- often hunting for more than a second.
The G1 is slightly larger than the E-P1, which has no viewfinder and a fixed LCD, but again in my opinion, the size differences are not functionally important. Both are small, but neither is small enough with a lens mounted to slip in a pants pocket (unless you have very big pockets, and don't mind walking around with a large bulge in them.) The best way to understand the size of these things is to look at them together -- I've not yet seen a photo comparison that doesn't cheat in one way or another. In my opinion, both can be considered ultra-light shoulder-strap cameras, smaller and lighter than M Leicas. They are both very packable. The lenses can be used interchangeably. The E-P1 is a better-looking camera, with a higher-quality feel to it. The E-P1 has inbody IS; the G1 has lens-based IS.
The E-P1 has video, if that's important to you (and if it is, then you may consider the E-P1 to be the more functional of the two.) The upcoming Panasonic GH-1 will also have video, but will also be more costly. For me, if video was important, I'd add a small video camera to my kit, rather than try to get by with a small combo camera like these; they are so small and light they are virtually uncontrollable, at least by me; everything jiggles.
There have been complaints about the E-P1's "low-res" LCD, compared to the G1's. The difference is visible, side-by-side, but the two cameras have to be side-by-side for me to see it, and if I hadn't been told about the difference, I doubt that I'd notice. The E-P1's LCD is larger than the G1's. I do use the G1's twistable feature, and like it a lot.
Because the lenses are interchangeable, I bought the E-P1 as a backup for my G1, rather than buying another G1. They make a nice combo, each having features that the other lacks.
JC