finished the stealth character - level 50-something, did all the quests. Made a Breton mage and to be frank magic is pretty overpowered. For one thing, you can power-level it, which is massive. then take Conjuration to 100, get the twin-souls, get the dremora-lords, drop 2 of them and assist with your lighting bolts (Destruction) or whatever. I miss the stealth stuff, but if I ever really need to go stealthy, I have muffle and invisibility (illusion) . . .dragonskin armor (alteration) has an 80% reduction in damage which is the max you can get with any armor anyway - so basically, you can do anything the other class' can do.
my build is illution to silent casting (yes, magic does double damage in stealth too), destruction to expert (master level stuff has too much of a ramp-up to be useful imo), conjuration to max, and maxed out alteration. With the 30% reduction from magic from alteration, the 25% you get from the gift of mara, and the 25% from Breton blood - I have an 80% magic damage reduction off the bat - after I get enchanting to 100, I will make me some nice robes and gloves and boots that have magica, magica regen and a little fire and ice damage reduction. . . and you can easily become immune to magic and almost immune to physical damage.
the first 10 levels are tough. . .