The insiders preview they have atm is stable as, AFAIK, bugless. Updates, although we know we will get some, aren't really _nessasary_.
There are some enterprise features coming, they will change the keyboard, and we should get timeline and files on demand via the Cortana and onedrive apps respectively. Additionally app updates via UWP on PC, means no matter what current win10 phones will continue to receive new features.
UWP isn't like other mobile app platforms, its the whole endgame for windows in general. If support for current win10m ended tomorrow, it would still get new features via apps for years to come. And given the intensive focus on bugfixes since CU, its looking pretty polished on the insiders build.
No worries there unless a) you are an atypically huge app user, like a business traveller b) you atypically are huge into smartdevices, like smarthome gear - some stuff works, not all stuff does c) you have wearables already that aren't compatible (plenty of wearables are, but with win10, better to buy the wearables _second_ than hope the ones you have already work. d) paywave - if you want this on your phone it only works currently in the US - you can get paywave smart rings, cards to go on your phone and loads of alternatives, but if you specifically want it on your phone, and live outside the US, it doesn't work.
None of those are really "normal" use situations, but it bears mentioning, because these three areas are win10m weak points. If you are one of those people, you might make it work, but you should be aware.
Also, and this is more generally pertinent - there is few banking apps. I use lastpass to get into the website instead. Nearly as convenient, but not exactly as good. Only "workaround" I've needed, but there's that (May change after WoA releases, that should really boost UWP because windows laptops and notebooks are very popular devices)
Win10m has great OS features - vertical scrolling, live tiles, Cortana text replies while driving, inline text replies, PC interopability and a beautiful UI that's a joy to use. Obviously iPhone has more support, more smart devices and more apps. Apples and oranges in a way.