As soon as the Mac version of GreenPois0n came out, I went ahead and jailbroke my device. It wasn't the same eye-candy that JailbreakMe was, or even Comex's first jailbreak, but it worked and I didn't have to wait long. Here's a few quick things that I immediately noticed.
LockScreen PIN Delay
After a fresh reboot or a respring, I can no longer dive right in to tap the PIN to access my device. The problem is either a delay or the first tap or two is not recognized. But it definitely slows me down a little bit...