I just watched it, and it's quite decent.
There's a lot of those awkward introductions that most network shows have. It plays a bit like the opening act of every rom-com, but it works overall.
Since there's going to be comparisons to the CW shows, I'll get into those as well.
The acting is quite above-CW. Don't get me wrong, a lot of the CW actors do improve a lot with time, but just that in the beginning the acting tends to be noticeably sub-par sometimes. While Supergirl's acting isn't particularly standout, it doesn't feel off either. Jimmy Olsen's acting might need a bit of work, but it wasn't noticeably bad either.
The lead is immensely likable as well, they cast well to find someone you could root for immediately, kinda like Barry Allen on The Flash. The sidekick character is a bit cheesy, kinda like a dialed down Cisco, and I can see people being annoyed by him, especially people who are not used to the slightly cheesy style of shows, but again, he's not a deal breaker.
The side characters on the whole didn't feel as strong, and the writing for them was a little weak. The boss character will also possibly annoy people, but she wasn't as bad as the trailer would have indicated. All the cheesy stuff in the trailer, that's all there is, they showed all of it, and the rest of it is quite normal.
The villains too aren't particularly compelling yet, and I know it's the pilot, but the Wells tease on The Flash was amazing. Perhaps the supposed main villain they showed at the end will turn out to be good, but in the (admittedly very little) we saw of her, she seemed like a cookie cutter villain. Daredevil and Flash, and even earlier seasons of Arrow, have kinda spoiled us when it comes to main villains, so there's pressure on Supergirl to get one at least somewhere close.
Not a fan of the TV show title card logo, but I suppose they can work on that if they choose to at any point.
It's not a fantastic pilot by any means, but not as bad as people claimed it would turn out to be. No deal breakers as of yet.