It's a nice engine for people who want to get going quickly and it's very artist friendly which is ideal as coders shouldn't be fucking around with art related tasks. On PC/Mac, I could definitely look into Unity but for mobile I'll avoid it for another little while as it IS pretty CPU heavy. Their C# like script language (mono) runs on a mono-emulation layer which interprets the byte code at run time which is nice to make it platform agnostic but it will cost you! I'm not sure if this has been upgraded to do JIT compiling.. I would hope they did but a lot of coders I know who are doing mobile projects with unity have speed as their biggest complaint! Even simple games with minimal geometry and shaders doesn't run nearly as quick as it should!