I do *very much* like the crop. I also do like that you can take a picture, and then add it to the app. I've never found taking a photo within iNat to be very effective for me (since I mostly do animals that RUN AWAY and there's a lot of lag time). There's always room for improvement, but I think Seek starts out very strong.
I agree about the treasure hunt approach. When I'm working with kids, I like to emphasize that there is a lot of the world that scientists still don't understand, and if they look closely enough, they might be the first person to see X or discover that Y has expanded its range.
A fun note re: Pokemon. Back when Pokemon Go was a huge craze, I would go out trying to hunt Pokemon, but I kept seeing bugs and herps and switching back and forth between iNat and Pokemon got to be too much of a hassle so I just got *really* into iNat :D There has been a lot of criticism of apps like Pokemon Go, but I think getting kids outside is the biggest challenge, and it achieved that very well. Once they're outside, they can't help but notice all the stuff they never saw before, and one spark of curiosity is often all they need.