I have experimented with Tactical and Easy. I found the beginning *very* difficult in Tactical: it's hard to be "tactical" when you have no skills and only 1 or 2 potions. Once you get past this point and especially if you visit the Battlegrounds, it's quite OK but still fairly hard.
Bear in mind loot drops are random, so that may enter the equation. Playing Easy (sorry, I'm at work - can't remember if that's the right name), I was 2 levels higher and at least 50% more potions towards the end of Act 1. Two levels is significant: that's another 2 skill points and 10 ability points.
I currently have hundreds of potions but some of the battles are requiring multiple potions per monster to defeat, so I'll chew through them quickly. I obviously need to visit the Battlegrounds and level up.
So...be prepared to be frustrated on Tactical early on but it's not too bad after that. If you like the "action" part of an action-RPG, I would choose an easier option. That's too much from me so I'll leave it there. <img src="/ubbthreads/images/graemlins/smile.gif" alt="" />