Upgraded to 2.0 as well through Kies last night.

Felt like using a new phone all over again.

Aside from the excitement, found a few things that were quite a let down.

1. Built in image editor is no more.
2. No built in Twitter and FB apps.
3. Where's the live wallpapers?
4. No more left/right swipe contact to call and sms, now you can still swipe, but then it presents you with the call/sms etc buttons and you have to touch it again, meh...
5. I tried to shut off all the background running services, especially those that will 'secretly' synchro, but still, the battery life under performs compared to 1.2, this is a big disappointment.

Things I like about the new 2.0:
1. Finally, folder organization!
2. Shortcut apps to main screen

That's about for now, need to spend more time with it, also need to re-download all my apps as they're all gone after the update. :\

Is it something like connection error issue?

If so, go to your connection settings, make sure you assign the connection profile to your 'samsungapp', then it should fix your problem.