Bandaid solutions were implemented to solve basic and superficial flaws like Joker's inexplicable retreat and crash landing, the magical appearance of your squadmates on the Normandy and why Hackett suddenly attempts to communicate with Shepard on-board the Citadel. However, each one of these introduces more completely irrational consequences and questions. How Normandy wasn't shot by Harbinger as a result of landing right near the Conduit beam it was supposedly protecting, why the Normandy decided to land on a random jungle planet for some rest and relaxation after the biggest galactic war ever, or even why the ridiculous stargazer sequences is included when the epilogues suggest a huge technologically advanced spacefaring galaxy, are just some of the new issues introduced.
We could always just forget everything after this
What's arguably worse is the fact that BioWare did change their ending despite saying that it was unchangeable. The destruction of the Mass Relays, which was specifically stated as an outcome from the Catalyst no longer occurs. In fact, this line has been removed entirely from Shepard's exchange with it. After BioWare staff insisted "the relays are only disabled" despite the Catalyst explicitly stating they would be destroyed, and The Arrival DLC indicating the destruction of a Mass Relay was equivalent to a star going supernova, BioWare were seemingly forced to recant this assertion from the Catalyst. Other changes, including adding a completely new ending where Shepard can refuse the options presented and instead ensure the galaxy's defeat also is a change to the ending. In doing this, BioWare have seemingly attempted to appease fans, but ultimately all they've done is admit through their new content the original ending was grossly flawed and poorly executed. To simultaneously insist it was not in any way flawed or that fans "misinterpreted" the original ending is a misappropriation of blame. The blame lies squarely on one end: BioWare's.
Furthermore, the Extended Cut does nothing to address the fact that the Catalyst's arguments classically beg the question (i.e. it uses its own assertion as proof of its assertion), are logically inconsistent for every provided option, and the ending is inherently at odds with virtually all the key themes pushed by the series up until this point. The Extended Cut is a series of bandaids across a series of mortal wounds that do nothing to address the ultimately fatal blow to the coherency of the Mass Effect series.
It's okay if everyone turns into this. We have green lights instead of red! That's makes it good! You watched Star Wars, right?
That the Extended Cut just presents a new flaw for each one it attempts to solve is a testament to its failure. I thought for a while on how I would describe the Extended Cut to Mass Effect 3 in one word. Eventually I managed to think of something suitable, though it applies equally to the original ending, and it disappoints me greatly to have to say it: