I've been using Samsung's Galaxy S from T-Mobile aka Vibrant since July. Overall I'm happy with this phone except its GPS is crap and the software is laggy. But now that Nexus S is out with Gingerbread, still running 2.1 (Eclair) and waiting for T-Mobile/Samsung to update to Froyo sounds ridiculous, and i decided to take on the root thing.
It turns out, as mostly expected, that the rooting and installation process is very painless and the result is pleasant. You can just go to XDA to root the phone, install ClockworkMod recovery, backup the current stock ROM (JI6 for me) and install Eugene_373's Ginger Clone R2. Took me like half an hour and now I'm on Android 2.2, without Samsung bloatware, with 2.3 based UI and keyboard. This ROM runs really snappy, the battery life is greatly improved and it has Wi-Fi tethering and I have an unlock code so I could use this phone with b-mobile SIM next time I visit Japan.
Oh, you might ask why not CyanogenMod. It's just not ready for Galaxy S Family yet.
I'm not envious for Nexus S anymore, except the front-facing camera that i don't have :)