Not at all. Unity is the engine I use, these engines are immensely valuable to developers like me, I can't invest years into building my own stable core right now, and although it has its rough edges and problems, it suits my projects very well. Builds to all sorts of targets, too. For my latest project I'm using the FMOD middleware for positional 3D audio. On the graphical asset side of things, I paint everything in Photoshop, and animate it in the amazing animation software Spine (which has an open source Unity runtime).
Oh man, Spine is amazing. The latest 3.0 release has some great new scale features, and the fact that you can browse all the runtimes on github and submit patches is just the best. And the community is great too, lots of support on the forums, and bugs I've reported were fixed in days. So yes, Spine is absolutely worth the investment.