Action sequences in this show are so hard not to laugh at. You've got the brilliant "fire pistols from one moving vehicle to the other" plan to trap a super-being, and the whole mid-air slap fight...and then, for some reason, they decided to make the biologist sister also the hand-to-hand combat expert. Supergirl just looks like she has zero power behind her punches, and nothing seems to connect at all.
Oh, and the general rule is that kryptonians under a yellow sun are some of the strongest, toughest, most powered individuals out there. So an evil one shows up, who is bigger, stronger, and more experienced...and you DON'T call your cousin? "I wanted to show that I can do it on my own" does not fly.
But, yeah, she's cute...and the show isn't worse than the other superhero fare out there.