When the snow comes here that'd be a very handy robot to have around, especially if it can shovel too. Maybe it can also scan a valid ID to add a shot of "other flavoring" if you like.
Putting my wishful thinking aside, the polite mechanical decoration is very well mannered. Isabella looks pretty all bundled up, especially with the wide hat to allow for her hair's width while also eliminating the flatness up top. It looks like you had a bit or trouble with her right eye, judging by the smudging and angle. Maybe if her mouth was tilted more then it would have been easier to place? Regardless, a great smile is a great smile. Phineas' excitement shines too, and his winter clothes are flattering as well.
Of course, whenever I look at a PaF picture like this I have to wonder how Doofenshmirtz's activities will disrupt the invention's function or existence.
Yeah, Isa's face was a bit difficult (I now notice that I completely forgot to even give her eyelashes), but I think generally it's correct. I mean, head tilted upward, one eye closer in perspective, pupils aligned...Phin's pupils are a bit misaligned. :/
Doof adds an Ethicinator that changes Mr. Snowbot into Deranged Mutant Killer Monster Snow Goon. >:3
The funny thing is that I noticed there weren't eyelashes on her right eye, but somehow my mind blended her hair and hat into a single piece that covered them; that was only because on her left the thicker line for the bottom edge of her hat registered as an eyelash. I'm slipping! (The mind does Escher-like stuff sometimes when looking closely at details.) What stands out the most is that her far pupil appears larger, from the smudging and possibly also from touching the other outlines. On top of that, the erased portion makes it look like she has a thin iris around the pupil. (Kind'a cute actually.)
It really comes down to a mild case of The Sketch Factor. If you mirror the picture it may be easier to spot (and I even see a few more things that way...). Actually, that's what led me to finally notice the knitting detail on Phineas' hat.
Some people will say to always draw the pupils on the same horizontal line regardless of orientation to make them look right. That's BS. I've since learned the real problem is that these folks can draw only with the same perspective every time. You are doing it right.
"Deranged mutant killer monster snow goons? Not on my watch."
It's true, I left a lot of sketch marks on this one...I think I may have been in too much of a rush. Still though, I didn't have to change much from my initial freehand for it to look just as I wanted it to.
Nope, the pupils should be aligned according to the angle of the head, and size should be determined first by expression, second by perspective. That's how I've been doing it, anyway...