I thought the first couple of episodes were a little silly and almost stopped watching but as my interest grew I actually researched the original JSA which was from the Silver/Golden age of DC and were before my time. It was fun the way familiar names kept coming out of the woodwork. Anyway, at a bingable 13 episodes it's worth checking out if you're into this kind of stuff.
It is a bit hit and miss as the season goes on. I have not seen the finale, yet, but I am pessimistic for a season 2 to be as good due to budget constraints (they're losing a lot of budget when they go to CW only). I'm hoping we don't get 4 episodes with super hero battles and 9 elevator episodes.
I'm a little over halfway through the season and I like it. The JSA stuff is well done, but I expect that - Geoff Johns being the creative force behind it helps that, because he is a HUGE JSA nerd and his stories with them were usually good. It gets a little goofy at times, what with all these super villains all burying themselves in this one town and having kids, but they do a good job with the ones they chose.