I've done some Symbian C++ application development, it is quite difficult to get your head around, and it's particularly hard if (like me) you have to switch between multiple development environments (Palm, though not so much now, Windows Mobile, desktop Windows, THEOS, Linux, HTML/CSS).
But I've heard the "no documentation" thing raised in a lot of places and I didn't find that to be true at all. In some cases, there was too much documentation, and what was there was too complicated for a newbie. Sample code was the same - there's loads of it, but it's hard to split out which parts of the code control which feature.
I know that once you get into it, though, it's quite straightforward to build some pretty impressive apps. There's a good community at Forum Nokia (mentioned above) and I get some inspiration from talking to some of the devs they wheel out at the Smartphone show in London. If you can spare the time, it'd be worth your while going down there to have a look as you're not too far away, it's on at the end of October. Not a massive show by any means, but worth a look.