Johnnygaijin has already proven themselves quite brave - this was their first sewing project! It turned out great.
They shared some helpful notes:
I made the Simon shirt. It was my first real sewing project. I got a sewing machine for Christmas and figured I'd just jump in the deep end. The sleeves are touch too long. I figure I'll make another one right away to lock in what I've learned.
The hardest part was attaching the sleeves. Distributing the sleevecap ease evenly was super difficult and I certainly didn't do a great job. Any tips there would be appreciated. Flat felling the sleeves was beyond my ability too, I ended up just fake serging them with a zigzag stitch.
FreeSewing is planning some tweaks to the default sleevecap ease and cuff ease based on the helpful feedback. Check out the latest version of the Simon pattern on FreeSewing.org.