Given the current state and future uncertainty of the OS, I wouldn't commit to spending much money on it.
I just switched from the 950 to an Android and can say with certainty that unless there are major overhauls in the OS, I won't be using W10M as my DD.
Best case scenario, the 'newest' W10M phones will be supported for another 1.5-2 years, though given how little MS has developed the OS recently I would suspect it will be less than that. Those phone have already been out for a while, and as far as I'm aware, nothing new is planned (and at least confirmed).
We've all been waiting for a Surface Phone (or more recently a Surface Mobile) for years - don't hold your breath.
There is some promise with W10 on ARM but there isn't much info on how this will translate into phones. That will likely be my next trip back to a Windows phone device... if it comes to fruition.
W10M had great potential and some truly unique features when it was released, but since then the potential hasn't really materialized and the competition has caught up on anything that was differentiating (continuum, cameras, etc.).
All that said, if you like W10M and can live with the uncertainty and limitations, they aren't bad... just limited.
There was a time I'd recommend a Windows phone to everyone, but that time has well passed. It pains me to say it, but I really can't imagine a time when a Windows phone has an advantage over an Android or iPhone (unless comparing the best Windows phone to an old competitor's phone).