Definitely. And it's one of the few kids shows which is episodic in nature, but has an over-arching continuity. I love that structure and the idea that there are such things as cause/effect and character growth, rather than everything is back to square one before the next episode.
I agree. My nieces spend a lot of time at my place and I'll admit I'm a Spongebob fan from way back, but other than that, most kids cartoons are pretty lame these days. Phineas and Pherb does has a surprising sense of humor, and I'm most certain I would've watched it constantly if it would've been on when I was 7.
It's been a while since I've seen a kids toon that I enjoy as much as my daughter and my sister's kids. There are some really laugh out loud moments and a lot of self-referential humor (even a bit of 4th-wall breakage).