I bought Samsung Star 3G on September 2009. I was looking for a touch screen phone with an affordable price. I had short listed 3 phones Samsung Star, Star 3G and Nokia Xpress Music.
The star is good(also cheaper) but does not offer 3G on the other hand 5800 have everything but price tag was around 16500(on September 2009) so I bought Star 3G(price: 11300). Firstly I noticed about the touch screen response of the phone, which is really good. Its much better than the 5800. The phone does not come with any memory card(can support up to 8GB) or any other accessories That 5800 was offered but you also save around 5000 as well. The Built quality, overall look and feel is good and easy to use.
Typing sms, emails and surfing the net is really fun. Head phone sound quality is good and phone in built speaker is also loud and clear. Camera and video recording is good, rather I would say average. Flash quality is also good and you can able to take pictures at nights(without sufficient light).
Battery life is also ok. It will give you around 24 hours back up(when fully charged) if you use the camera or play the music for a longer time. Network coverage and the call quality of the phone are really good(which is more important).
Recently nokia cut down the price of 5800 and now its cost around 13000. So if you looking for a rich multimedia touch phone then go for 5800. I guess if you can spend 11000(though I don’t know the current price of star 3G) then you can also bear 13000.
So my suggestion would be nokia 5800 because you will get lot more goodies than Star 3G. Otherwise if you want to stick with Samsung then you can go for it or corby(recently introduced), which is some how value for money.