As I've learnt a bit more about it, my opinion is changing about W10M. I'm noticing that there does appear to be some reinvigorated interest from developers now that it ties the desktop to the mobile. I still really think MS dropped the ball and should have worked on improving the transition from WP8 to W10M much more smoothly.
I really want the platform to succeed, I should give W10M a bit more of a look in (i'm on a L920, and just want a reliable phone, so never tried any insider builds), hopefully MS uses some of the feedback they get to declutter W10M though. I think they start to worry and change things which don't really need to change, although, it does appear that they are trying to change the app issue.
I think that really it's the chicken and egg scenario with the apps and adoption rate. You won't get one without the other, and vice versa. For quite a while, the lack of apps didn't bother me, as I had what I wanted/needed. More recently, however, with a few apps closing down, I can't say it's quite the same. I'm keeping a close eye on microsoft maps and navigation. I'm quite a fan of here drive, so until the MS app behaves very similar, I'm not going to consider W10M, seeing as I can't have here drive on it.
I also think that a few quality games would go a long way to help the platform. I know that they're looking at all platforms, but they should try to leverage xbox with more quality games that work on the phones, on xbox, on desktops and try to make it much more than the plethora of microtransaction games available.