N900 could be interesting in this regard.
maemo looked interesting, but even the firmware update method was archaic and extremely over complex. From what I remember it only worked if you unplugged the usb cable and plugged it in at exactly the right point or something! (swear to god, this was in the README).
Maybe it's all changed now though.
I do not know re. if the UI experience has changed. I can see how N-series tablets can appeal to hackers who like to modify the software that is running on their device. From this POV having a full-fledged Linux on a mobile device is a plus. But N710/N800 was indeed less slick in terms of the user experience than Apple's devices.