I don't know where to start but since the new version of Unity the whole lightmapping is a real pain. In the previous version i could use my own lightmaps and now i'm stuck with the lightmaps generated by Unity. If they would be as good as the lightmaps generated by Unreal engine i would say okay. But Unity doesnt match the quality Unreal engine has. Neither the quality from Vray or the soon to be announced baking from Ottoy. So why would you remove the option to use your own lightmaps. And then you have the option to generate lightmap uv's on import. That is nice, if you are to lazy to create it yourself. But if you opt out unity is stil messing with my uv's. And then the time it takes to bake!!! I'm probably doing something wrong. But doing things wrong is not hard either. Because of the lack of good documentation. Why on earth would you release something if it's not documented. Last year i needed to use the loadrawtexturedata. it took me a whole day to figure out how to use it, since it was not documented at all. it's a shame. I was really happy with Unity and since the day it's available on PC i have a license. But for unity 5 we didn't buy it yet and im looking more and more at other alternatives.