Watched the first episode yesterday. I'm reserving judgment.
My big problem is that I'm finding it hard to buy their Jim Gordon, mostly physically. He just doesn't look like young Jim Gordon to me. He may grow on me, but Tom Welling never convinced me as Clark.
Second problem, what is with Barbara going-to-be-Gordon senior? They couldn't just have used Kate Kane? Maybe they thought fans would be mad with them for making her bisexual...but I dunno. I don't think I like this, and I would like it even less if she became Batwoman. Babs just can't be first.
(And Ivy can't be her real name, but people would never have realized who she was, so...)
On the good side?
Nice recognizability on the characters. Penguin was instantly recognizable. Their Selina was awesome and I am pleased they chose a darker-skinned Hispanic actress for Montoya (and didn't straightwash her). The overall visuals for Gotham itself were fitting - nice balance of neon and grit.
Still. Reserving judgment. It might be good, it might be terrible.