I gave up on this game about 6 months or so ago, because I hated mages, and couldn't get into it and the controls. I decided to try agai recently.
First of all, mages are possibly the most useful class in the game once you get a feel for the ontrols. It may take a little longer to cast their spells, but they made certain fights on the second floor MUCH easier for me, fights I don't know that I woulve survived without ridiulous reloading, or incredible patience.
For those of you mage haters, something I found useful was the casting chart in the walkthrough as a reference. Once you can grasp it their Aoe spells are irreplacable. Hopefully you can get more interested in the game because of it.
Marcello: They took out four of my guards! Angelo: (whistles) Marcello: .......yes well..
It doesn't take much work to write a script for AutoHotkey to let you cast spells by pressing keys. If you do it correctly you can run a party of five mages and have them all casting spells fairly quickly. Of course in my experience scripting things so that you can use the keyboard to attack instead of the mouse can break the game, at least at low levels. This holds true, albeit to a lesser degree, if you use AHK to use a 360 controller with the game.
Stop complaining. I could have done this more painfully. - Dryad from Sacred 2.
My mage is an indispensable member of the team. I have improved frostbolt and it is great for freezing enemies in place, especially in combination with a backstabber.
Monster Hunter 3 Ultimate
Coming March 2013 to Nintendo 3DS and Nintendo Wii U
Grimrock is fairly well designed so that almost any combination of classes might be workable. All mages? No mages? All rogues? You could get away with almost anything.
The main problem I have with mages is that it's hard to have enough skill points to cover every single useful spell.