It never was a "game". It was a tech demo Lucasarts made for their in-house engine that they struggled to turn into a game. After the E3 demo with the original character they changed it to a young Han Solo game and then a Boba Fett game before it was cancelled. Visceral's game (Ragtag) would've been much better than it, and the Jedi series are better than what it would've been as well.
They weren't struggling with 1313, in fact they had a pretty solid vision for it and an all-stars team of veteran developers were working on it.
The character you saw in the E3 2012 demo
was the main character they initially wrote the story for, before George Lucas busted into the LucasArts offices in spring 2012 and "asked" for Boba Fett to be the protagonist instead since he was a popular character. 1313 was never a Han Solo game.
Regarding the game itself, it seemed like a very competent Uncharted clone with, once Boba Fett was introduced, some very cool gadgets-based gameplay and combat encounters. Those that saw early footage from the canned E3 2013 demo say it was spectacular.
Ragtag was also fucking amazing, and no, Respawn's Star Wars Jedi games don't come anywhere close to the quality of Amy's game. Ragtag and Visceral were killed over EA not wanting to run a studio in San Francisco as well as to continue to invest in linear, story-driven, singleplayer games (Fallen Order wasn't as linear and was being made on a much tighter budget than what would have taken to wrap up Amy's game, which was already running late due to the hiring freeze EA had imposed onto Visceral), not a quality issue.
And it's not me saying this, but literally everyone who worked on or saw behind the scenes material on both of these projects throughout the years.