Anyone gone to iOS 4 with success?

[eyeRobot]

I have a 32GB 3GS with 3.1.3 on 05.11.07 Model MC137LL, I rely on jailbreaking as I need it unlocked.

I've read that I can upgrade to 4 with custom firmware via Snowbreeze and then Unlock with Ultrasn0w.

I just wondered if anyone had physically done it and whether everything was working well? It's working great at the moment and won't bother upgrading if it's going to cause any bother.

Thanks in advance for any replies.

[blackgold11]

I still did not try it, but I believe it will be slow on 3GS. I have an iPod touch and i upgraded it to OS4 yesterday. It was very slow which stopped me from doing the same on my 3GS. If anyone has done this, it would be great to get your feedback especially on the speed issue. Thanks.

[eyeRobot]

Should be quicker on the 3GS than the touch.