Ok, please don't flame me for this, but in my opinion maemo has loads of apps for just about any task, most of them great.
But many of the new maemo specific apps were not entirely up to what you'd expect from kde/gnome apps in general (not at all strange when considering the time frame they were developed in).
Although they were about as good as apps on other mobile platforms.

Performance, hastily done user interfaces, loads of missing features, and let me re-iterate; performance: A lot of the software written for maemo needs optimisation and lots of it.
I also think maemo hasn't reused enough code, a lot of reinventing the wheel going on.

And after the release, it felt like devs moved onto other things and those apps haven't been improved too much since.

I'm talking about the phone, address book, calendar, notes etc. (firefox is slow to begin with, so not much can be done about it, and we have opera anyway)

None of this is a show stopper, it's just my opinion that 3rd party apps weren't a problem, but possibly some of the 1st party ones.