Had it less than a week, but these are my preliminary opinions..

Summary: Decent enough phone with some good ideas, but ultimately not a completed product.

Good: On a basic level, it fulfills its prime directive, that being a cell phone with text messaging, web-based mail, an attractive interface, and a selection of applications available for over-the-air download.
-It seems to carry a decent signal and
-streaming music seems to work well and is clear to hear.
-It has a nice little task bar of a couple of tasks available to launch from and you can easily change desktop wallpapers, including adding your own.
-Bringing up email or IM messages you can easily delete them by holding the message line and dragging it to one side and hitting the Delete button.
-Typing on the keyboard is not as good as the Blackberry, but it's not bad overall.
-Battery life is actually better than I'd heard and does not disappoint.
-I like the swipe-up to close apps. Very neat.
-I like hitting the middle button to 'card' apps and being able to switch between them.
-Camera is awesome, in my opinion.
-NFL Network is pretty useful if you like that kind of thing.

Bad: Without a Homebrew installation not much beyond the basics is easily done.
-You can't forward IM messages. There also seems to be no holder that holds a history of messages.
-The only real way to expose the keyboard is to place a thumb on the screen and move it up. In very short order this smears the screen with fingerprints and oil. This results in a habit developed to frequently wipe the screen. Better would be some nub or rough area on the bottom to use the thumb so the screen doesn't need to be touched.
-When you get a notice of an email on the bottom, you don't have an option to swipe-delete it there. You have to click it and go into the email app and delete it there. Response to clicking the garbage can and having it delete is incredibly slow (I generally just swipe-delete it).
-To Reply to an email it opens up another instance of the browser. It should operate within the same instance. Related: There are no text descriptions of some of the email buttons. Both left buttons do the same thing: bring up a Reply browser.
-You can't (without some serious reading into), easily customize the quick-task buttons on the bottom of the home screen.
-Opening the browser doesn't really give you a customizable home page. Like many, I prefer to open a browser and have a large set of tools and information resources available at my fingertips. This is absent on the Pre.
-There is not a media/device management divice created by Palm. Using iTunes is a hassle because Apple keeps making efforts to lock Pre users out from using it and iTunes itself is a huge memory and cpu hog. Having a small and useful program by Palm to organize things like the old Treo users had would be far more useful.
-The default 'DOC' viewer is very limited. You can literally open only MS Word and Wordpad documents in it and that's it. More; formatting for both this and the PDF viewer aren't very customizable. When bringing text up you usually have to rely on pinch-zooming. A word wrap capability would be far more useful and something the old Treo's did by default.
-Video support is fairly sucky. Only mp4 appears to be supported (I tried about 6 or 7 different formats and only mp4 worked).
-Google Maps is decent but you have no ability to send your location through IM/email without a third-part app.
-Help is terribly sparse and basically un-help-ful.
-No easy way to hide or remove apps on-the-fly (like for um... Nascar... or whatever ).

Other: Sprint TV doesn't stream well at all.. but this is a network issue and not the Pre's fault. There's very few apps in App Catalog, but you can't really fault Palm except to suggest the phone might have been released a little early and that perhaps developers should have had a longer crack with the DK so more apps would have been available at launch. Couple that with bugs and things left out or overlooked and it's not exactly a finished product for the masses. It works and has some very nice bells and whistles, but not a finished and polished product. Perhaps in another 6 months or less this may change, but some work definitely needs to be done on it.