This was easily the best episode, best written, big surprises throughout all the way to the very end.
Although I too have a problem with Supes, "I was pulling punches foo, let me show ya sumthin".
Dont get me wrong it was the coolest action sequence Ive ever seen from the big S, easily.
But, did he not give his all when he was fighting Darksied inside Brainiac's asteroid base thing? Or the other times he fought him, like after he recovered from getting brain washed an leading Apokolip's armies? They should have shown the punches from supes to be so much that they ripped large chunks of atmosphere temporarily off the planet, making some of the other superhero's stop their fighting cause they briefly couldnt breath or something like that. So we at least get a believable, tangible reason for Supes holding back all these years. And maybe the reason he can stop holding back now is because it took him this many years to master his powers fully enough to do it without killing everyone around him and on the planet.
Personally I would have liked if Darkseid would have toss the anti-equation aside laughing that his new powers go far beyond that now, but then supes would break free of the agony matrix thing, crush the kryptonite dagger, get all pissed off and say something like, "warm up's over" with a horrified expression on Darkseid's face. Then show batman a good distance away and suddenly a giant explosion leveling most the city and batman watching a fiery meteor flying with ridiculous speed into space. Then Flash would pop up,"What the heck is/was that?" and Batman would reply,"Unless I miss my guess, thats whats left of Darkseid".
And to add more credibility to the full power scenario at the end of the episode, Batman an Superman would have a private discussion. Batman would get really pissed at Superman for not using his full power sooner, all those other times the league almost lost. Even question why they need a league if he is that powerful, like "Is this supermans version of the cub scouts? Charity work?" but then Superman would let him know why he didnt use it sooner.