[Apologies for the long post]
I'm also using a Palm TX. This is my fourth Palm, and easily the best of the lot. I had given up on Palm after my Tungsten T became practically unusable, but after struggling for a year without a PDA, I got a TX and it restored my faith.
Palms are certainly not perfect (the OS is a bit old-school), but they're really fast to use. If you need to scribble a note or look up an address, you want to be able to power-up, get into an app, do your stuff and switch off as quickly as possible. That's Palm's forte.
The TX is thin, lightweight, reliable, with great battery life, great screen, good features (WiFi, bluetooth)... and it's affordable.
I'm using it with The Missing Sync. If you get a Palm, you must get TMS and forget the supplied Palm desktop software.
What else..
* There's no other PDA with the features of the TX at anything like the price. PDAs don't hold their value well, so it seems sensible to spend as little as possible to get the job done. Only... don't forget all the add-ons! (Case, TMS and other apps, screen protector).
* The WiFi works very well and connecting to networks is a piece of cake. I hear it's nothing like as easy on Windows Mobile. Email and web browsing work just fine on the TX.
* Get a screen protector. Otherwise you will eventually scratch the graffiti input area with the stylus, and then the recognition disintegrates a bit.
* Best case I found for it: Piel Frama
* Battery life excellent, esp if you turn off BT and WiFi when you don't need them. Which is quick and easy to do with the little control panel bar.
* Flash memory is a relief after the Tungsten T. No more losing all your data if you don't recharge the thing for a while.
* Great Palm apps that I consider essential: Checklist (better than the built-in ToDo), SplashID, TCPMP (video player - I can't get the supplied "Media" app to work at all)
* Want a good game to kill some time on long trips? Warfare Incorporated - realtime strategy. Easily worth the $20 or whatever it costs.
* I wouldn't bother trying to use it as an MP3 player. It's just too clunky, and the audio quality isn't up to much. Get an iPod. There really is no substitute.
* Syncing over Bluetooth is convenient, but a little slow. Use the USB cable if you're in a rush or need to transfer big files.
The Windows Mobile competition? I agonised about this for ages before buying the TX, because I felt (and in many ways still feel) that the Palm OS is dying a slow death. But I had a play with an HP WM unit for ten minutes and pretty much hated it... seemed like all the same ridiculous jumping thru hoops as you get with Windows. I've read several reports from people who went to WM, and ended up getting a Palm again because WM, although pretty, was awfully slow to use. But what do I know?
If, like me, you primarily need a diary/notebook/address book replacement, Palms are great. The "DocsToGo" Spreadsheet app and Word processor are good too.
If you need to draw, do serious word processing, or want to use your PDA for gaming, Windows Mobile may be a better choice. It's more like a PC in your hand. Is that what you get a PDA for though?
Still hoping Apple enter the market though! That would be very cool.
HTH