Shawn Blanc, in his review, notes the single most awesome feature:
Now, I don’t know about you, but my wife and I don’t shop at just one grocery store all the time; we shop at like six. In Checkmark 2, I created a location group with all the grocery stores we shop at. Then, no matter which of those stores I show up to, Checkmark will remind me of any items I’ve added to that group. (Gosh would I love to see shared reminders with this.)
Not having that was the single biggest annoyance for me, great work adding that in.