Absolutely, the 20 f/1.7 is a great lens on the micro4/3. I liked my Panasonic GF1 a lot, and I'm sure from what I've read the Panasonic GF2 is a worthy replacement for it.
I've heard that they're really quite different cameras. The GF1 is a much more technical, shooter's camera, while the GF2 is more dumbed down; settings are buried within menus and the touch screen is used for most navigation; it's more of a high-end point and shoot. Sort of explains why the GF1's price remains so high in comparison to its so-called successor.