1. Android has nothing that compares to the functionality of Siri. Period.
2. Siri works as long as you have a data connection of any sort (Siri needs to connect to Apple's servers in order to work...this is why she wasn't working as well when the phone came out on the 14th...Apple's servers were overloaded and couldn't handle all of Siri's requests).
3. Having to root your Android to get the same functionality/OS upgrades is hardly functional. I'll be the first to admit that iOS still misses the mark on a lot of things for me, and I will be jailbreaking 5th iPhone when it's available.
4. The Nexus *seems* nice and all, but until it's released and there are relative comparisons, it's all just specs. Same with the Razr.
5. I'm honestly disappointed with the lack of some upgrades that I expected with this release (larger screen, more RAM), but the quickness over the 4 is just astounding. On the flip side, even with conditioning and cycling, battery life has me a bit on the flustered side. If not for my external battery case, I'd be screwed every day.
6. Tell Siri you want some weed.
7. I've had no problems with 6FL on my 4, and there have been no fundamental changes in the connection port of the phone, so the snap-in adapter should work, as well. My phone charges just fine, and plays music just like it used to.
8. Siri works on the 4, but it's not available to the general public yet. I'd also have some concern about Apple's servers noticing that iPhone 4's are connecting to the Siri network, and realizing they're likely jailbroken phones, and what they might do as a result.