What is known about Beethoven's opinion of Mozart's music?

Answer 1

Performing a Mozart piece for two pianos (or arranged for two pianos by Mozart) Beethoven looked over at his fellow pianist and said "We shall never be able to do anything like this." Beethoven was in awe of Mozart.t

A young Beethoven played and improvised for Mozart who said of him "mark him well, he will make a mark on the world some day.'

Answer 2

Well, I haven't looked up any quotes or anything, but it is known that Beethoven modeled his 3rd Piano Concerto after Mozart's d minor Concerto, K466. I would say that means he had a good opinion of Mozart's music and compositional skills.