For improvement I suggest the following edits:
When lining up the pattern for each piece try to account for what stuffing it will do to warp the fabric. For example on Shuckle's head, the seam in somewhat uneven. This is because Shuckle not only has a difficult head shape but it got twisted while stuffing.
It looks like you mastered his rounded body shape, great job! The only piece that looks a little uneven is his front right leg. However, that really isn't an issue at all because he IS in fact a turtle! If that happens to bother you though, just use the same pattern for both of