PRO: Please read my comment below.CON:1. Plays limited MP3 formats.2. Memory Stick Duo Pro is still more expensive than other media types. (Though, the included 512MB might be sufficient for some people.)3. I wasted money buying a Bluetooth headset because I can't take the head phone off from listening to MP3s.COMMENT:Simply put, I can't let go this phone. I listen to MP3 all day and this thing just keeps on going... (over 10 hours of continuing operating with MP3 playing only runs off about 2/3 of the battery). I don't know how SonyEricsson does it, but the battery life REALLY REALLY impresses me (not to mention how great the sound quality is). Listening to the songs without worrying about ever missing a call is one thing, but listening to songs without worrying about the battery life is just priceless. What's worst than you have 20 GB of songs that you can not listen to because of a sucky battery life, for example.Plus, A device in such small size (about the same size as a business card in width and height + 1cm ) yet packs EVERY feather (ex: 2MP Cam, Voice Recording, FM Radio, Email client, PDA functions, Flashlight, USB Flash drive, Build-in modem, and mighty Bluetooth - for wireless sync, file transfer, and dial-up networking, and many more) that you could name is just damn amazing; not to mention how easy it is to operate. I can swear that you can get to ANY function in 3 clicks or less. From time to time I was amazed by how genius SonyEricsson is in making the operating system of this phone. I've been using Ericsson and SonyEricsson and played with other phones; nothing is comparable to the intuitiveness of using the W800i. It beats its predecessors and other brands - try it in some stores and you'll know what I mean.Bottom line, it's awesome in design and yet does everything beautifully without dieing. I would recommend this to everyone who wants to consolidate their PDA, Camera, and iPod/MP3 player (not to mention all the charging cables/adapter associating with those devices) all together for one pocket-friendly, compact device. This is a device that a geek like me had been waiting for.------FOLLOW UP------This is the latest status and my findings:You could get even better battery life if you turn off the Bluetooth and turn the screen light low. So, I did that and I get MORE THEN HALF (Between 2/3 and 1/2) of the battery life at the end of 8 1/2 hours of usage (includes continuous MP3 playing). I made about 10 calls and 2 min. per call at least + few snap shots + changed the songs from time to time.My finding is: I could transfer files much faster when the phone is turned OFF. Apparently, my laptop (with WindowsXP) can still see the phone when it's turned off. Via an USB cable, I transferred 12 MB of songs in less than 40 seconds.