Hello all,
I was considering (finally) moving up to the newest version of Unity, and I wasn’t sure of the best way to keep track of any changes between the two versions. It’s easy enough to look up the new features and the corresponding C# syntax, but is there anything else I should be doing to get “up-to-date”?
When it comes to scripting not much has changed. All you will have to worry about is looking at the new features that Unity brought into the Editor. If there is any functions or anything that are not usable, Unity will give you the usual Obsolete warnings and tell you which functions to use. It’s a pretty easy conversion, and you shouldn’t have too many issues.
If you have a project that you are currently working on and want to update half way through just to be save I would make a back up copy of it just in case, but you should be ok for the most part
Prefabs/Instantiation are handled differently in Unity 4.0+; you’re able to preserve the active/inactive states of the parent and child objects in the prefab. So if you were say Instantiating a copy of an object/prefab which had some inactive objects in its hierarchy, before it would activate all every object within it by default, whereas now it preserves those states (as it should!). So bear that in mind for any strange bugs cropping up. 
+1 to fenderrio. That’s probably the most insidious change to watch out for.
Also, please, please, please use namespaces. You’re not the only one who’s going to write a class named, say, “InputHandler”. 
Excellent insights. Thank you all.