And if you look at how the final battle went, it wasn't even about the god child that threw this game off. This whole series was about fighting the Reapers. And when the game finally has Shepard confronting the lead Reaper, Harbinger in the flesh, all he does is zaps you and flies away without uttering a single word to you. Kind of out of character since in ME2, HIS DEFINING TRAIT WAS TAUNTING YOU INTO BELIEVING YOUR STRUGGLES WERE FUTILE! This is like not having Darth Vader show up in Empire Strikes Back at all until the end where all he does is cut off Luke's hand without saying a thing. And Luke doesn't even acknowledge him like how Shepard doesn't even acknowledge that Harbinger is right there in front of his whole platoon.
And creating another human Reaper? Here's the problem with that. The humans that Shepard runs into on the Citadel are all dead. That's not how it works! The humans needed to be digested/processed alive in order to get the materials needed to make a human Reaper. If they didn't need to be kept alive, what the heck was the point in going through all the trouble in taking humans alive in the first place?
And the confrontation with TIM was so ill-advised. Instead of dealing with Reapers, we've got to deal with this knock off of Saren's final confrontation from Mass Effect 1, complete with him struggling with your persuasions to killing himself. And of course Hackett somehow knows Shepard is not only alive, but also on the Citadel in position to help out. Hackett, you can't get standard Earth military history right, so how is it you know Shepard is on the station when everyone on the ground reported that no one made it to the beam?
Worst of all, we have the god child who tells Shepard some things that don't make any sense at all in context to the previous games. Instead of Shepard being a strong and defiant character like she's always been, she conforms and obliges this entity... BECAUSE SHE BELIEVES IT! That's the stupidest thing Shepard could have done. This entity just told her that he's responsible for all the death, pain and suffering that everyone in the galaxy, including Shepard has had to endure. His reasons for justifying his actions are based solely on speculation that synthetics will destroy organics. A speculation that Shepard can disprove right outside where the battle is taking place! We've got Quarians and Geth fighting together against the Reapers. We've got EDI, a now unshackled AI who was against us in the beginning now fighting with us by her own choice. Hell, she's even fallen in love with a crippled organic who can barely walk! All of this, and Shepard still takes the word of the god child over everything she's experienced!
So don't tell me that this ending doesn't ruin the franchise. This was supposed to be Shepard's defining moment where everything she's done in the previous games culminated to this point. Instead of honoring her actions from both ME3 and the previous games to shape the conclusion, Bioware chose to go with something that can be reached regardless of what you did in everything. Which basically means that all Shepards everywhere are now conforming cowards.