5230 is a good phone. I have used 5800 XM and they share the same hardware & software. It lacks wi-fi, but is good in other respects. If wi-fi is a must, you can also consider Nokia E63 as I suppose you don't particularly need a big screen.
As for samsung, first thing is, I found the capacitive screen very inconvenient (I have used my friend's corby many times). Since you don't have a stylus, you are forced to use the finger every time, so if you have sweaty fingers, it becomes almost impossible to operate. And also for some reason I found that it simply doesn't respond to my touch although my friend never faces such a problem (He concludes my skin is a good insulating material

). So do try one if you decide to go for it.
Also the Menus & other UI elements are not as good as they should have been. For example, if you receive a missed call, it shows the number of missed calls as the total of all missed calls in the call log. So you might often come across things like "You have 17 missed calls" and jump at it, and such other things. But the widgets are good.
One thing, if someone knows why the capacitive screen doesn't respond to my fingers, please enlighten me!