i recently have been learning python in mobu and there are some other posters here who know a lot about it.
they seem to have made a lot of changes to python since jason parks’ masterclass in 7.5. a lot more functionality is exposed in 2009+ so it is much easier to do some things.
as far as difficulty goes, it depends. in my limited experience, i’ve found that if you’re creating things (constraints, objects, characters, whatever) then it is really pretty easy to operate on the objects because all of the constructors return objects that you can work with. finding handles for objects that already exist makes things a fair bit more difficult, and the docs haven’t gotten any easier to work with.
ui stuff is easier in the new versions, and there is a visual ui layout plugin that i use to block out ui’s. you can find it here: http://neill3d.com/tool-programming-in-mobu/ui-builder
it’s good but a little buggy and it’s missing some of the new ui features like HBoxLayout and VBoxLayout which allow you to put multiple controls in a single region. i do find it very useful to prototype the ui and then export to .py so i can modify easily after that.