I'd wait.
I actually just returned a 3GS because it didn't feel like much of an upgrade compared to my 2G. I wouldn't recommend it for a 3G owner at all.
Wow. I'd think there must be something wrong with the 3GS you used.
I've got my original 2G and refurb 3GS side by side. The difference is surprising. 2 bars with AT&T on the 2G. 4 on the 3GS. Apps open quicker on the 3GS (2-4 seconds for some), data is pulled faster. The screen looks better on the 3GS. I'll keep mine...