I had a NX-70 Clie, the Sony specific stuff was nice but it felt like an old Palm Pilot that was souped up to the max, the hardware was nice, but the screen was wobbly and the bling silver paint wore off quick, I ditched it and went for a Z 5500 (my new C-860 arrives next week). For me, in my opinion, there is no comparison, one is a glorified Casio-esque databank, one is a UNIX workstation. mmmmh.. workstation..
I am happily running my 5500 now with the internal RAM kept empty, 32MB MMC for storing apps and fonts, 512 CF for MP3 and OGG music and DivX, MPEG, ASF movies and about 300 books, got the new Battlestar Galactica miniseries on it right now and several albums, its the kind of pocket computer I always dreamed of as a kid (back when I had a Casio PB-100).
I REALLY recommend tkcVideo and tkcPlayer, they are superior to the Sony offerings IMHO. I don\'t miss the Clie at all, it was a nice looking paperweight that turned heads, the Z is a workstation and that is how I look at it and use it, much to the envy of my salivating friends who are desperately waiting for theirs.
I do not use Bluetooth or such stuff, so I can\'t help there.