The first thing is that this phone uses Dolby Mobile in its music player. It is ASTOUNDING. I've had an ipod touch over two years, and Dolby kicks *ss and wipes the floor over the ipod.
Music: I had no problem transferring my MP3s via the software although i would recommend Windows Media Player its so much faster, and it kept all my files/folders/artists in order as i know them on the ipod. (If you have AAC files you will need to get itunes to convert them to MP3).
Camera:The still camera is incredible and the post-tweeking of your pics presents endless possiblities. The dvd quality video camera is also extremely good quality.
Movies: To be honest, if you don't want to play around with video conversion software, dont bother, as you will become very familiar with the words 'Not Supported'. But there are some very easy to use software packages such as Cucusoft DVD converter or AVS DVD converter. You can only convert to certain types of files (i use H264). Also the player will not play movies with sound file sample size greater than 16-bit or with a bit rate lower than 16kbps or a sample rate lower than about 32000Hz.
I cant praise this 'phone' enough. Its the only satisfactory piece of kit that can handle music, movies, photos/video, has a memory card slot and can make calls(!) that i know of. I will of course use itunes for downloads, but they will go straight onto this handset.
The browser is also very good. Navigation is a little fiddly but ive gotten used to it.
Lastly, as far as i can tell, the arena is no faster or slower than an ipod touch to operate.