well, i used 2.5 when i first started, and even from there, it was a lot differeont from maya 4, the interface is different, some of the menus and tools are different, paint fx was missing, a lot of the modelling tools have improved over time, the first maya wasnt all that gr8, well, 2.5 isnt all that gr8, but if you're used to 4, you should be able to get by ok, ud just have a bit of a problem finding some of the tools