I agree with @mattSydney here.
Unity seems to be crumbling under its own size : my bug reports rarely get any coverage ; even the simple ones about typo & errors in the documentation are ignored ; Feedback site is a 4 years old cruel joke (or maybe even more old, I arrived on Unity 4 years ago) ; new features keep being added while the existing ones are still incomplete years after their 1st release (eg: Mecanim that was released in v4.0 and needed to wait v5.1 to be finally relatively feature complete).
Personally, I wouldn’t recommend Unity to a team. As a single developer, it’s still a good choice, but one has to plan for the inevitable roadblocks he’ll get if he doesn’t use Unity in the generic ways it was intended to be used (or not so generic => can’t even redefine the input from within the game…!!).
So Unity will make you save years of development, but will also likely make you lose months of development to bypass its issues & shortcoming, and recreate from scratch a feature that you had thought to already be in Unity, but was unusable because it missed something indispensable (and often it’s an obviously needed thing).
Just lately, I got 2 annoying bugs : 1 has been reported 1 month & half ago (with a project, but not by me) and there’s still no fix so far ( => Update to Unity 5.1 = too bright GUI [EDIT: bug is back in 2019.1] - Unity Engine - Unity Discussions ), and another one, with a project by me, 2 weeks ago, and still didn’t get any answer from Unity (about previewing in the Editor small audio file, which gives totally bugged sound).
Always asking “post a project” when reporting a bug, when a normal project will be several GB big, requiring several days to upload, and containing a lot of confidential data (I’m not willing to give my source to anybody) is not a good way to proceed.
Asking to “create a project” is also not a good way ; it takes time, and as right now it feels almost no one check the bug reports, it feels like a total waste of time anyway
v5.1.2 seems to be the 1st version ever that I can publish my game in good conditions (if no nasty bug arise, I still didn’t check too much) ; I started to work on my game more than 3 years ago, and I’m near release, so it seems I got lucky, but I can’t imagine the stress I’d have been if I was ready to release 1 year ago, as what I had in mind wouldn’t have worked in U4 without a lot extra painful & sub-optimal bypassing.
And no, I couldn’t have known at 1st that it wouldn’t work in U4 because the documentation didn’t have a word about the limits I hit during development (about physics engine).
Did I mention the lacking documentation ? 
Anyway, I could go on for hours about all the shortcomings of Unity. If you want to see some of them, you can check my post history, as usually I post about them in the Forum…
Thus said, it’s still a great engine, it’s just the unfinished parts that are (really) annoying !