A motorcycle is as close to flying as you can get without leaving the ground.
Long time pilot here. Grew up with airplanes. Love them enough to own one for over a decade now, and that takes dedication!
(and money
)
By all means go on a flight with him.
1) Getting your license from a school will cost you anywhere between $4000 and $10,000 depending on your area of the country, what kind of plane you rent, and how quick a learner you are.
2) Find out if your friend is a Certified Flight Instructor ("CFI").
3) What is your relationship with him? Does he want to give you a "taste" of flight, or is he offering to bring you all the way through to your pilot's certificate? What does he want in the way of money? Fuel? Rent? His time?
There are some people out there, typically retirees, who own planes and look for any excuse to fly. I've known some guys who have only had to pay for fuel to get their licenses, with "free" use of the plane and free instruction. That would be about as good a deal as there is. There are subtleties about what he can charge you, but you will learn that as part of your "book training."
Once you understand what the offer is, you can compare to what it would cost at a local flight school.
All in all, a BIG thumbs up to you. Go for it!