This qualifies as being gaming related and there's an ongoing discussion about it so I'm putting this thread here.
Unity is quite possibly the best development engine that has ever existing in the gaming industry. To say that I've started to like it a bit is the understatement of the century. I had my doubts about it at first, there's no denying that, but I honestly think that any company that isn't using this engine or something very similar within a couple of years is going to be regretting it. Here's why I think that's the case:
1. Unity ports native-run versions of games to PC, Mac, iOS systems (iPad, iPhone, etc.), Wii, 360, and PS3 with really minimal effort. If I set up my code properly to begin with, I can build 6 different versions of the same game to run on 6 totally different platforms in less than half an hour. Building the same game to run on different platforms usually takes a company a number of different people and all kinds of time for coding adjustments and so forth.
2. The Unity development team is very open to suggestions for improvement and enhancements. I spent a long while with these guys at GDC talking specifically about things we'd like to see their engine be capable of doing. Super nice folks.
3. If you make something that works with the Unity engine and want to share with other people you can sell it directly through the Unity Asset store and make money. I plan to do this with a couple of things I'm currently working on for Phoenix.
4. The total and utter simplicity of the thing. At first this had me extremely nervous because it seemed far too simple. Bad conclusion for me to draw - the simplicity of the engine setup actually enables Unity to handle extremely complex code on a really simplified level so it loads and processes things much faster. The whole scripting setup is just brilliant and super straightforward. There is a brief learning curve if you're used to coding things to death in other engines, but once you get used to it life gets so much easier.
5. I'll stop at this one - best free version of a development engine I've ever seen. The basic version of Unity is free forever and it does like 97% of the stuff that the Pro Version does. If you're a really small developer you could totally make full games using just the basic version no problem. And the basic version still builds PC and Mac versions of games totally and completely free.