If you compare it to the more serious neo-realism of the Nolan films, again you're not gonna enjoy it. If you compare it to the darker and more gothic Burton films and are disappointed Keaton isn't still playing Batman, of course you're not gonna enjoy it. It's sandwiched between the fandom of the Burton and Nolan films while simultaneously blamed for leading to Batman and Robin.
Batman Forever may be the most unfairly criticzed super-hero film ever made.