They seem to deplete your magika very quickly, I mean, both times I activated the ward in the college of winterhold, My mana depleted before Tolfdir even cast a spell at me.

Lol I know, I was like "TOLFDIR, THE DAMN WARD IS UP, JUST CAST YOUR DAMN SPELL"

I usually just dodge things instead of trying to block them. Though I guess doing both at the sme time is good just incase you don't move in time.

Wards are useful you just have to reduce the cost a bit and use them at the right time. They also give you armor. I like using my wards once i reduce the cost to something more reasonable.