Umm...I suppose this is the part where I should say "Exhibit A!" in reference to what I said previously. There's a pretty good reason as to why A New Hope is the template looked upon in respect to story structure. The build-up, character introductions, etc. fall at a rate that keeps things briskly going along. Empire's 2nd Act? Eh...gotta say that's the weak spot.
So now we're just going off the rails to shit not even associated to pacing...to criticize my comment regarding pacing. I never stated Empire wasn't the 'deeper' film of the two. Your subjective feelings of how you find ANH's climax as 'boring' doesn't really matter either.
But the main reason why the ending was boring was because of a pacing issue in its build-up. The movie spends far too much time with the main characters in the Death Star, and once they escape, you barely get a couple of scenes with the rebels planning the attack and suddenly it's back at the Death Star again. It wasn't handled well, and it made the ending quite unfulfilling because of how the Death Star suddenly went from "most dangerous place to be" to "the thing to destroy" in only a few minutes.
Then again, I see this pacing complaint also directed at Guardians of the Galaxy Vol. 2 and its second act when compared to the original, so I guess I just can't hope to understand. I'd much rather have a movie that takes its time and develops its characters in the second act (which is often referred to as the "development" part of a narrative for crying out loud) than one that is just nonstop action and excitement and shit going on all the time.