Quite nice phone
I bought this phone a couple of days ago to my mom for her 75th birthday, and I've been playing with it for a bit to teach her all she needs to know. My own phone is N82 and I can say that I really will miss the touch screen when I finally hand the 5800 to my mom.
The GUI works pretty fast and I like it since I'm used to using S60 in N82. I've never used an iPhone but I'm a mac user so I can understand that probably iPhone's GUI is much slicker both in the eye candy and in the usability. But then again S60 gets the job done just nicely. But I do wish that Nokia and Symbian would take S60 to the next level and keep making it better and better.
The 5800 has got nice speakers, the gps works fast and well, the screen is bright and the touch screen works pretty well both with fingers and with the stylus. I actually haven't remembered to use the plectra at all :D, but I can actually understand why it's included. I don't have the biggest fingers (I'm an average sized male) but it takes a little time to learn to write with two thumbs with the full screen keyboard. I'm not sure if the current full screen keyboard is the most efficient one, but then again I've only used it for very little while. Actually the biggest reason I got this phone to my mum (besides the GPS) is that she can finally write text messages easily, either with the stylus with choosing the letters or by writing the letters on the screen and let the text recognition system translate it.
So, after a few days of use I really like the phone. It's not perfect, but in this price range I think it's got quite a lot to give. After N82 I'm not that fond of 5800's camera, since it's not really that great, but then again N82 is more expensive. My next phone probably will be some later touch screen model, maybe N97, but I do wish Nokia keeps the prices down like they did with 5800.