This episode actually had a solid concept: instead of having a change of heart, Yondu delivers Peter Quill to Ego, leading to the formation of a proto-Avengers team in the 1980s.
Michael Douglas, Laurence Fishburne, Kurt Russell, and more return to voice their characters and what does Marvel do with this stellar cast? Absolutely nothing. Familiar characters are quickly thrown together with a very sloppy script. Unfortunately, Hemsworth's Thor is also wasted, receiving some horrendous dialogue. The episode is chock-full of misplaced MCU humor, tonal inconsistencies, and plot conveniences.
This is an absolute waste of a great cast and likely a very large budget. The script should be the most important aspect of film/television, something Marvel's What If has forgotten.