Downloaded both the Safari and iTunes updates last night, then iOS4, then left the phone connected from around 10.00pm 'till 7.45am backing up/installing new OS/re-installing apps, and when I left for work at 7.50am it was just re-installing music/videos. Been playing with the folders function, and that I like a lot. Most new features won't work on my 3G, but the new 4G on Thursday will give me a lot more to play with. Letting mapping/nav apps run while I take photos is one feature I will use a lot, also having Tuneit running in the background will be really useful. I've seen a few forum posts saying iOS4 has made phones really slow, but mine seems to be running quicker at the mo'.