I used Waterloo Dark for the beer, though I'm not sure how much of a difference that makes. The celery didn't soften as much as I expected. It wasn't crunchy, but it was more firm than I'm used to. Of course, most of my celery consumption comes out of my slow cooker, which turns most vegetables into brown paste regardless of starting characteristics.
The last ingredient is "Popped popcorn, if desired". I don't normally desire, but I have a bit of regret that I did not pick up any popcorn in anticipation of this recipe. Presumably there are other recipes that call for this American staple, so I can correct that oversight.