Update includes:

• Decrease in call set-up failures and dropped calls  (I haven’t really had any dropped calls since I first used my iPhone)
• Significantly better battery life for most users
• Dramatically reduced time to backup to iTunes  (Now it only takes around 10-15 mins what normally takes 3 hours to finish)
• Improved email reliability, notably fetching email from POP and Exchange accounts  (Opening mails in Mail2web is still sluggish. As long as push notifications are fast, it’s fine by my standards)
• Faster installation of 3rd party applications
• Fixed bugs causing hangs and crashes for users with lots of third party applications

• Improved performance in text messaging  (SMS.app is more responsive now, but still no forwarding or MMS)
• Faster loading and searching of contacts  (Finally!)
• Improved accuracy of the 3G signal strength display  (I don’t have 3G)
• Repeat alert up to two additional times for incoming text messages  (Every 5mins. This is pretty handy)
• Option to wipe data after ten failed passcode attempts  (I dont wanna wipe out my phone besides I dont use passcodes and it looks to be broken on 2.0.2)
• Genius playlist creation  (I only have 2 genres: punk and grunge)

It took me >5 fucking hours to update and jailbreak 2.1. Why?

• I gave up after an hour of backing up my iPhone on iTunes 8. The progress bar is not even on the 25% mark.  I want to be able to restore to 2.0.2 in case my upgrade to 2.1 fails and I dont want to redo my games all over again.
• I fucked up my WinXP box.  As of this writing, the latest version of Quickpwn is Windows only.  Command-line shell access is required and thanks to my sister’s iPod, Windows is infected with this bar311.exe malware, which runs a shutdown script everytime you spawn a command prompt.  I tried to erase it in the registry, but I might have accidentally deleted an important key.  Now, any user who logs in is automatically logged out right away.  Sucks.  I should have just followed (again) that howto in TPC.
• The XP installer I used is an old one.  It only has SP1 slipstreamed.  I had to download the 300+MB Service Pack 3 because iTunes 7.7 requires at least SP2

NOTE:  To those wondering by Genius is not enabled on their iPhone 2.1, first you have to enable Genius on your iTunes 8 (IMS Account is required) and then sync.

There are some changes that weren’t included in the changelog.

• Making a screenshot now makes that camera shutter sound.
• The album name and artist now appears at the bottom of the song title in iPod.

• Apple must have changed the spacing between icons in Springboard.  Now, my dock icons are cut on the top part

UPDATE: This is actually a known bug in iPhone 2.1 and Winterboard.

• Load Earlier Messages.  I cant say if hiding older messages will show an increase in performance of the SMS app.