They also added many new controllable characters to the roster. If all you've ever wanted out of Extella is to roam the battlefield wreaking havoc with your favorite Fate series character (and they made the cut), then you're probably going to be a happy camper.
Extella Link's story and character development is bare bones. The story focus is on Charlemagne and he is the only character to get any appreciable amount of attention. The game shoves the old 'a new enemy appeared and took over everything and now it's time to be the rebels again' plot arc at you in what feels like the first 30 minutes, it feels so rushed. The main story is also very short - on Normal mode, taking a few breaks to go play Extra side missions even, completing all 3 main story routes only took 12 hours, and the story is really bad. I'm not even comparing it to something like CCC, even compared to the first Extella there is very little story-driven tension to make the battles feel more dramatic and meaningful.
If your main draw to these games was your interactions with (Nero/Tamamo/insert previous game character here) then you can forget it - they are afterthoughts in this game.
While the main story is incredibly short, the game's length is increased significantly by the Extra missions. While these are also very bare-bones when it comes to story, there are a whole lot of them to keep you occupied. So whether it's a short game or a long game depends entirely on whether you're the type of player who just wants to finish all the story routes and maps, or if you're a completionist who wants to complete all extra maps and all main story maps on 'Very Hard' difficulty. You could be finished in 10 hours (if you rush the main story and ignore the extra missions) or kept occupied for 100.