I don't shoot my IIa enough. Mainly because for a long while the frame counter was messed up (I've repaired that), and I only had the 2/50 Opton-Tessar, which makes me feel like I'm using a fixed lens camera. I have recently gotten a Nikkor 135 for it, and might be able to pick up a Nikkor 100 (unless I get outbid). But the lack of an affordable 35 keeps me from really embracing it, and having another rangefinder outfit of full kit (Leidolf) which gets more use.
I like the way it handles, the 2/50 is great (even though it needs a cleaning), and all the little quirks don't seem to make a difference on the outcome of the image. When I do shoot it, it depends on what film I have in it, and what the light conditions are on whether or not I use a filter, of which the orange is my favorite.
I bought mine because of the fact it was not a Leica. A metal shutter appeals to me more than having to fix burn holes all the time (had enough of that with FSU cameras). It was also much less expensive to buy than a Leica III(pick a letter) with lens. I hope to get a 35mm for it sometime this year, so I can give it something more than a monthly run through the shutter speeds, then back in the drawer.
PF