The OS's stability does leave a lot to be desired...
(And, because of its weird development models, the two best browsers are Blazer, which... doesn't blaze, is incompatible with a lot of sites, and requires a LOT of sideways scrolling, or Opera Mini, which requires a pirated version of the J9 JVM, requires lots of tweaking to run at all, and crashes left and right because the J9 JVM sucks horribly.)
But, they got the UI right, IMO. Simple is good on a device like this. Yes, it looks dated, although I've got PalmRevolt and Fonts4OS5 installed, and that helps a lot.
(Fonts4OS5 is also a good thing to have for Opera Mini, because Opera Mini wants to run at the large font sizes on Palm OS, and doesn't support the Opera Mini built-in subpixel-rendered font. So, Fonts4OS5 allows you to install a different (smaller) font of your choosing for certain applications.)