Really good mate
The animation is as spot on as it could be from someone who didn't actually work on the show with all the pro equipment. The characterisation is great too.
The only criticism I have is that Zim's voice isn't quite right; he's a bit more exasperated than that, but to be honest Richard Steven Horvitz has such a distinctive tone I doubt ANYONE will ever nail it. Gir is spot on tho, great use of filters to get the tone just right.
big things mate, I see biiiiig things for you!