Yes it's free to all mobile platforms now, which is a huge compared to before ($1500 for iOS etc.) http://unity3d.com/5
You do have to put up with a Unity splash screen. ..but if your app takes off then buy the full version for $1500 OR $75/month
Yeah the most important stuff is that you can now export everywhere without additional fees.
And anyway a little splash screen is nothing. Plus it's Unity, it's classy.
But when it comes to speed of development C2 is better. The real question is do we really need UE4 or Unity. UE4 is only handy with 3D, 2d has no point there. And Unity has a very good 2D engine but is much slower in terms of development. But it has however a better optimization possibilites and lots of sprite tools (like rendering polygons).
For modularity and code support Unity is the way to go. But for small projects and even bigs but where there is no sustainability and support (dlc and stuff) involved C2 does the job. You learn algorythm and you can't learn to code but it does the job.