Yesterday, I received a new phone (sgh-u600 black) from my company. Now I got two cool samsung phones E900i and U600.
There was posibility to take U700, but I frankly was not delighted by this model. It seemed to me too shiny. While it has more convenient scroll wheel in the middle and a nice buttons keypad. So I choosed U600 for it`s strong design.
First of all comparing u600 to e900i, u600 has bigger screen and it is much thinner.
The second think is central navigation near screen. On e900i when I was going throu menu I accidentally pressed sensor buttons, which warked as exit. On u600 you have much more space between navigation button and sensor buttons, so I haven`t yet pressed accidently them. This I think is big plus.
The next thing I noted for myself is camera. In u600 it is 3.2mpx. Quality of photos is quite hight. I shooted some, but as I haven`t yet trained I had not such good shots. One more think about camera here is that you can recognise namecards. Camera has a lot of settings.
Talking about software. I noted for me quite interesting application, called Smart Search. It is something like MacOS Spotlight tool. With Smart Search you can search in all posible places of the phone or you can filter by some criteria, for example by menu, by files. Another useful tool is Google search. Just press and you got field for search. And this quick search warks now everywhere, entering phone number in sms or just typing to call someone. Good MacOS practise.
I have already downloades opera mini. Tryed some feeds on it. Feed rendering looks just perfect.
Music also is much better on u600.
What I dont like about u600, to slide phone up and down I have to touch screen. So it fast become dirty. In e900i I can slide by navigation buttons.
That`s all I have noted for one day about samsung U600. If now I had to choose between u600 and e900i, I better choosed u600.
JokochiMerano 
samsung u600 is betta
Well beta or not, but works great. I still use it and have no problems with it.
I say what is his features.
i too moved from e900 to u600 black and gold. in my opinion, both amazing phones and demonstrate exaclty what samsung are about, great styling and ease of use, packed with technology. I do prefer the u600 for bigger screen and it looks incredible.