I've never used Google Chrome, but have been running the daily Chromium builds for a few weeks now.
It's down right shameful how fast Chromium is compared to Firefox, Seamonkey, and even Konq. Flash takes less CPU in Chromium than Firefox. On one of our modestly
powered machines (PDC 2140 1.6ghz x2), full screen high quality Hulu stutters quite often, in Chromium it is fluid.
On my E8400, watching Hulu in Chromium takes 19% CPU with 84M ram. Same clip in Firefox 3.5.5 take 27% CPU with 192M ram. Add to that the startup and shutdown time of Firefox that grows after usage, and the disk thrashing that happens because they want to put everything in an SQLite database, unless Firefox does something to compete with Chromium, I see it's user base going down.
Chromium is nice, I like it immensely, but it can't replace Seamonkey for me yet. My girlfriend used to run Windows in a VM just to play her flash based games, she hasn't had to since I put Chromium on her PC.
So flash on Linux isn't that good, and Chromium makes it usable. It is
faster than Seamonkey, but not fast enough - or Seamonkey is not slow enough - to make me want to switch browsers. If I found myself needing to close and launch the browser often, maybe. I usually launch Seamonkey once, and it stays running for a week or so.
SunSpider JS benchmarks
On this PC which ran that benchmark, in day to day usage, Konq is the fastest, then Seamonkey, in dead last is Firefox.