PC xcom looks better and has more armor selection, but I really like iPad versions' touch controls and portability. Gameplay and missions are identical.
As for productivity, 90% of what you can do on a PC (excluding resource heavy tasks) you can do on a tablet. There is an app for everything these days like office suites, and there are blue tooth keyboards if you need something physical to push. That being said, I do not believe in replacing a PC with a tablet yet, but rather the two can compliment each other