This is probably the first two sided PCB I've ever worked with. The previous version had a couple of hall sensors on the back, but this one has five - so fully populated on both sides. And when I tried to solder this up, one side of the components fell off while I was assembling the second side. Arg!

After some frustration with this, I had to fix the first side with a little glue, let it fix, then solder the second. This worked ...

but it's rather messy. Notice the yellow ink (I melted a work mat onto the components while working this out). It's moments like this that I wonder if cheap PCBA is available somewhere.

The board tests and flashes correctly; the next step is to embed it in a joint.