I'm sitting here listening to some Spotify music on myN900. I've started on a GTK+ based UI with kinetic scrolling and some simple search and play list handling and it's looking like it won't be too bad.

My question now is the following: Is it a waste of time and effort to try to package this for use for others since I'm not using Qt?

There are some Qt based community clients on the move already so the need for a GTK+ based one might very well be minimal.

So, what say you? Yay or nay?

I am building a simple app in QT. I find QT fantastic, and think that the new SDK tools are very good, but I got sadly disappointed by two things:
1. the inability to use the new Mobility API. I can't even get the apps running on the emulator. I am sure it is a case of not having the proper Qt install on my laptop (Ubuntu) but haven't fiddled with it. I ripped out the mobility part and just read the accelerometer directly from the device in the filesystem. This locks the app into N900 usage, though it can easily be refactored back to Qt Mobility later on because of the loose coupling provided by Qt signals and slots.
2. The difference between the look of Qt components on the device from how they appeared in the emulator. Haven't solved this one yet--I think it is just a matter of explicitly setting some object sizes properly, but it could be that they will appear differently when PR1.2 comes to the device, and I won't know that at all until it does.

In short, I think Qt development is somewhat held up by the wait for 1.2.. If you actually want to get it out the door and packaged for others asap, use GTK+ since you are already most of the way there. If you are willing to fiddle a little more, want to learn Qt, and are OK with the idea of making some changes down the road as 1.2 appears, try rebuilding what you have in Qt.

Learning Qt is one thing (just another tool-set) but I do find C++ loathesome. It's opaque and will make lots of things behind my back making both development and debugging harder unless it's "Hello world!" in the making.

Object oriented programming offers great ways to model the problem domain but I just can't get over how C++ fscked it up.