Well done.
I've done battery and SSD replacements in a couple of MacBook Airs. With a good instructional video from Other World Computing, it's pretty simple, though complicated (I used to tell my residents that heart surgery isn't necessarily hard, just complicated, don't confuse the two).
The hardest part is keeping track of the tiny screws and remembering, or noting, where each one goes.
As a matter of fact, I remember taking apart some "jellybean" iMacs and installing larger hard drives in those (It's that German pr0n, you know).