Essen is not anything close to the character from YO or anything like the early to late 90's character... she's slightly dirty.
Alfred is a straight up dick, and is sadly just playing errand man for Wayne's dying wish (which they somehow secretly knew they'd be killed one day).
Montoya/Allen have no right or reason to be older and higher in the system than Gordon. How will he be a commish over a bunch of people who have been working in the job a lot longer, seems stupid and different just for the sake of having them in the show. These people will need to look up to him, at this rate they'll be reluctant to at best because he is awesome... not because they want to strive to his goodness.
Falcone, being a 'pillar' along side the Wayne's in the city. LOL
Selina. Bah, they're trying to hard to wave the Catwoman stuff in our face and where is there to grow/go from here? She already has a conscious and such while being sort of bad just to make ends meet.
Barbara is whiny and nosey. Barbara has always wanted Jim to put down the gun so they could start a family, not be his sidekick on his war on crime.
I don't know... Smallville/Red Son/Earth One/BTAS/etc. all changed things up but to serve the story, premise, and such. The changes to this show don't benefit the show. It just seems like they changed things are made certain characters have comic based names just to say they have said characters in the show.
It's frustrating, if you're going to go out of your way to include Montoya bring in a young cop during s2 or s3 who will want to be part of Gordon's GCPD. Not some MCU lady who will maybe come around to him being a good guy. Just seems wrong...
Don't even get me started on Nygma or Ivy Pepper (ridiculous name).