yes, the show has become enjoyable. it's not quite my Batman, but it's actually closer to how a show should mature as the seasons progress, even a cartoon.
we meet the JLA in the final episode of season four. well, just cameos so far, except for the Martian Manhunter. Green Arrow has shown up in season 5, along with Superman (voiced by George Newbern, a welcome return).
naturally, it's nice to see more heroes. and these might actually be the JLA heroes I am most familiar with- Barry, Hal and Katar, which will be quite pleasant.