This is being touted as the ultimate Android phone, and I am myself considering getting it as my next phone, but there are a few issues/things that I don't like about it.
1. Confusion about the quantity of RAM. It seems that Samsung initially put only 256Mb RAM in this phone (test units) and later seemed to have decided to go with 512Mb. But seems that they they have sent out some phones (maybe a few initial batches) into the market with 256Mb RAM. People from the East Asia got this phone first and some of them have got units with 256Mb. They are reporting that their phones are much less responsive than expected. If Samsung has more of such stock, they may decide to dump them in India.
2. Not shipping with Froyo as default. I don't like firmware updates, If I have a stable product out of the box, I don't update it whether its a motherboard, mobile phone or anything else. (I didn't update my launch day 5800 till the firmware version 50 released) Since Froyo is being touted as the best Android release so far and its already out, samsung should have considered releasing the phones with Froyo pre-installed even if it meant a delay of a month or two.
3. Lack of LED Flash. I don't care about its use for the camera. but I have grown used to using the LED flash as a torch light. I have an app on my 5800 which allows me to switch on the Dual LED flash and the phone doubles as a convenient torch light. Its one of things I rely on my phone for on a regular basis.
4. A 4" screen on this phone makes it quite large and hard to keep in pant pockets.
5. Not having a metallic case or at least a back side . This is a huge premium phone with a 4" display and its thin as it can get. With out a metallic body/skeleton, its quite possible to snap this thing in two when you keep it in your pocket.