Both movies can give you a good laugh. Although "My Girlfriend is an Agent" is more entertaining and hilarious than "How To Use Guys With Secret Tips"; they're both enjoyable.
Both of these movies have similar vibes and more precisely they are adult comedy. If you had enjoyed watching Casa Amor: Exclusive for Ladies, you will definitely like How to Use Guys with Secret Tips.
I have to say...the story is different. But bare whit me. I think these movies humor is alike (kind of crazy). Editing is also similar. I think if you enjoyed 'How to Use Guys with Secret Tips' you are gonna enjoy 'Devil and Angel'.