Well it's been a month so now's a perfect time for this review.
You will have fun playing Gotham Knights if you go into it, not expecting a Arkham game.
Part of the reason why this game got the hate it did, is because everyone expected an Arkham game, yeah WB Montreal had a hand in the Arkham series with Origins and dlc's for Knight, but the system they used for the Arkham series, shouldn't be the standard, "why do you want to play the same thing you played, 7 years ago?"
As long as you do that, you will have a good time. The gear system and character customization really shine, and the combat system, while a major departure from the Free Flow system, is enjoyable if once again, you don't expect an Arkham game
The idea of playing as the Bat Family instead of Batman is also interesting as you get to see a world without Batman and how it changes things. The Court of Owls and the League of Shadows (or Assassins what ever you prefer) are also good enemies to fight.
The online co-op is also fun, while WB Montreal struggled with The Multi-player mode on Origins, this one is alot better, as it helps to have a buddy, helping you clear out rooms, fight big waves of enemies or help with Bosses. Honestly they get a major win here.
Traversal is amazing as well, with the reintroduction of Fast Travel points, the use of the Batcycle, grapneling and each characters own forms of Travel. Nightwing is the best, as essentially, you get to fly. Batgirl's gliding is also fun and brings back memories from the Arkham series, Red Hood's soul jumping is good and very useful, Robin's is okay, but definitely weaker then the others, using it for combat is extremely useful, as it has saved me so many times from a failed takedown. With the size of the map, all these help to get around.
All in all, if you go in open minded, you.will have a good time
With the recent Heroic Assault update, I have hopes that other villains from Batman's rouges gallery will show up, especially since there are very few, and you'd expect that with Batman gone, everyone would begin to make there moves.
At the same time, there is also a possibility to add other playable characters, like Batwoman (comic version, not CW), another Robin, or possibly Luke Fox's Batwing, if WB Montreal can brave creation of a flying mechanic.
In general I enjoy this game, and as Always you can have your own opinion, but if you are really looking to get Gotham Knights, it is a good purchase. but unlike me, don't be dedicated to buying the Deluxe edition, buy the regular edition and if you enjoy it,
You can decide if you want to look like Batman Beyond or a Jim Lee comic book.