It's entertaining TV, and my son is definitely enjoying it, and both my wife and I have been watching it with him with some regularity. I enjoy it, but it's definitely not top-tier comic TV.
Spider-Man is the main character (of course), but he's working with SHIELD, including Nick Fury and a small team of Nova, White Tiger, Power Man and Iron Fist. There are regular guest characters from the rest of the Marvel universe as well as lots of classic Spider-Man villains.
Having so much SHIELD involvement and gear is a bit weird if you're used to classic Spider-Man, but there's a fair amount of time with just Spider-Man. The spider-cycle irritates me a little, but it does also solve some speed issues that are just hard to explain with Spider-Man.
There's a lot of emphasis on humor, which works well with Spider-Man anyway. The writing is reasonable but not particularly sophisticated or deep, obviously targeting children. The animation is decent, and the voice acting is fine. Peter's got a nice sarcastic sense of humor, but he has more attitude that I expected, and maybe not as strong a sense of responsibility as I've come to expect for Spider-Man.
My biggest complaint is the way they incorporate a lot of cut scenes containing internal mental drama, voice overs, explanations and emotions including very anime-like tiny characters and melodrama. It's really heavy-handed and it's so frequent that it gets in the way of the story for me. Why reference an emotion with a fleeting expression when you can have a voice-over and some kind of ten-second illustrative animation? You can get a sense for some of that from the trailer above.
It's not available in full-season form on DVD, so if you want to watch it, the simplest approach is probably to go to iTunes (not available in the Canadian store, of course).
As of this writing, the second season is airing, but not yet complete. There is some suggestion that its fate is TBD, but almost two seasons already out there, I don't feel like you need to worry about whether or not it gets canceled before you watch it.