None of them really succeeded in delivering anything more than an iPaq or a Palm Pilot and a mobile phone awkwardly squashed together in an ugly package, and they all required you to use a stylus that all-too-frequently got lost or broken. In the case of the 770, it didn't even have a phone! (To be fair though, in its favour it was the first device I saw that had a really good mobile web browser app).
Until the iPhone, "smartphone" really meant putting "groupware" [1] functionality in a mobile phone, and just having an Outlook-a-like on a phone clearly wasn't appealing enough for the mass market: in fact it was just downright boring...
The biggest difference with the iPhone aside from the capacitive touch was that it delivered an excellent mobile web browser alongside a reasonably decent phone, and all that other stuff was just an afterthought.
In retrospect I'm amazed that nobody else realised that the web - the same technology that transformed the internet from a niche technology into a must-have in the mid-90's - was the killer app for a smartphone (As I alluded to above though, kudos to Ari Jaaksi's team for at least trying with the N770 etc., even though the rest of Nokia seemed to be utterly clueless).
The 5 years from 2002 to 2007 were interesting, but in hindsight seem to share so little with post iPhone industry.
It was however, impossible to upgrade the software at that time (the OS), which rendered your device obsolete every time a major WindowsMobile version was released. This is happening again with Android and I can't say this is a very good idea.