I agree - desktop BS2 is great, but the mobile app has limited capabilities. It's fine for carrying around a number of recipes (e.g., handy at brew club meetings when someone asks for recipe details) and as a convenient reference guide for styles and ingredients. It also has some nice timers, tools and converters (that I honestly don't really use). I do wish it had a way to carry my shopping list for me from the desktop version to my homebrew store - I have to print it out now (how 1980's!).
I don't miss not being able to formulate or adjust recipes on the mobile version. I would rarely have any need for that, and I'd much rather do it on a full screen and keyboard over my phone anyway.
All things considered, the BeerSmith combo is the best commercial product(s) I've found. YMMV