The game has been great so far and I haven't run into anything too hard on normal (until this fight). But now I have to fight Letho in the elven ruins and he is pretty much impossible. Am I missing something or is he just ridiculously hard. He seems to have an insane amount of health.

Edit: Managed to beat him. He was actually pretty easy if you spammed quen, even if it took forever to wear him down.

Did you use a swallow? I'm having problems with him as well. 

Did you use a swallow? I'm having problems with him as well. 

@Tokubetsu said:

Did you use a swallow? I'm having problems with him as well. 

No. I just made sure to have quen activated at all time and rolled around the room. Every time he dropped his shield I did two light attacks (sometimes followed by a heavy) and rolled away again. Took a long time but was much safer than any other strategy that I tried.

Keep Quen activated at all times. If he's got his Quen up, don't even bother attacking him and just roll around. Once his Quen wears off, hit him with the Aard and hit him two times with strong attack, rinse and repeat.
Throwing knives and bombs also work well, if his Quen isn't up.

TIPS to beat Letho chptr1 fast and easy:

I did not use queen at all.
You can beat him very very fast.
Use Aard (force push) a soon as the combat starts. This will make him stagger while casting Quen and interupt the spell.
Get 2 heavy attacks in.
Dodge away.
Use Aard to stagger.
 Get 2 heavy attacks in.
etc...

Note that sometimes it is best to wait for him to start casting before instantly casting Aard, this way he will never get a Quen out and will not be shielded.
If he does manage to shield himself, just roll around for a bit until it goes away.