That's really cute! I really like Greg's character design. Samantha is pretty nice as well. The background and colors are quite serene and calming.
There is a problem though. The lines. For the most part they're fine. However, the lighting you used on some parts (Greg's shoes) makes it look like there are random white pixels just sitting there. The lines on Samantha's....pocket(?) also bother me because they just seem incomplete.
And those grocery bags are too tiny (unless Samantha is already bigger than the average person).
There are some flaws, but I like your style. Welcome to Newgrounds! I'm glad you're finding it neat.