Hm well right now they basically bombed Unity 5 off the planet - I mean, seriously, when you're going to choose an engine to pay monthly fees for, I can't really see the point of paying 75$ per month for Unity without source code access when you can get Unreal with source code access for 20$. I mean, come on. Of course, the UDK was a fucking mess to work with compared to Unity so far, but judging from all the footage showing the new workflow that Epic released so far, I think they really upped the game in that regard. Especially the videos showing one of their artists presenting what he made in a few hours without any real programming skills look incredible in that regard, the results honestly look better than a lot of what hobby devs manage to do with Unity in weeks.
And technically, well, there's nothing to talk about, UE4 IS one of the big guys, along with Frostbite and Cryengine, and hopefully Source 2 when it's revealed, and Unity has always been a rough approximation of these big players.
My biggest fear is that we'll now get a wave of crappy "Indie-" titles based on Unreal, just like as we got and still get due to Unity, that actually are nothing more than really bad hobby pojects.