Absolutely fantastic! It's great to see a conversion like this I have a few comments on the sculpt:
What makes Buzz who he is is the over sized cheeks and the attitude in his poses. Of course you are limited when it comes to keeping the realism. You can't go all the way, but if you look at these two photos you can see what I mean:
Maybe he would fit a face mass like that.
And if you pose him more sleazy with raised eyebrows you can still keep the realism, but at the same time capture the character Buzz Lightyear.