It does sound easy, but if he is sincere you will be able to determine that over time.
Unfortunately in this day there are ways around the NC he has promised you.
Here are some of the things my WH did:
Wrote and sent letter of NC - NC lasted 3 days
The cell phone in which I had access to the account would be set out for me to see; however he had prepaid cell phones that he gave to POSOW and also went and got an additional cell phone in his own account that he hid from me for a long time.
He deleted his FB account, but simply re-activated it later.
He had various personal email addresses that I was unaware of.
Be wary of how he accounts for his time.

Snoop, snoop, snoop - and always verify. I did a keylogger on the computer, that was the best way for me to verify what was going on.

I hate to sound so cynical, but that was my experience.

Hopefully your H got scared and wants to recover marriage, I recommend counseling with the Harley's. They can help you determine the best course of action and help determine if your H is sincere.

Dday:12/31/09-Found MB 01/03/10
D final 11/15/10

"I dare you to find some time and some place to be silent for longer than usual; a few moments, a few minutes, a few hours. Listen to your heart, listen to your soul; and most importantly, listen to the silence to see what it sounds like and how it speaks to you."