iPhone 3Gs issues...?

Hi, I'm new to the forum..
anyway, i was wondering if anyone else's iPhone was working GREAT before they installed the iOS4?? I installed the iOS4 and then the iOS4.1 and my phone is running like ****!! I was trying to use the camera the other day and the phone literally froze (you could see the phone was moving through the viewfinder, but i couldn't take a picture, return to the main screen or even turn the phone off, i had to reset the phone and wait for it to turn back on before i could use it!!) i never had any of these issues before iOS4!! What is going on with that? I love the iPhone and all my other mac equipment, but the iPhone issues have been pissing me off pretty bad!! Let me know who else has issues and what can be done about it. I'm about to take the **** thing to the Apple store and have it replaced for the 3rd time since i bought my original one in January (yes, i'm already on my 3rd iphone since January 2nd 2010!!!)
Thanks!!

Is this a 3G or a 3GS? Did you upgarde or do a restore to OS4 and then manually re-add you apps, music etc. I have read that issues such as you describe can be adressed by restoring the phone to iOS4.X and then manually reloading all of you data/Apps etc vice just upgrading and then restoring from a backup.