I use iBrewMaster on the iPad, and they have an iPhone version as well. I really only use it for brew-day tracking of ingredients, etc. The current versions are a little to buggy to use on a regular basis. The inventory module, which they admittedly released too early, is buggy, and tends to crash the app.
I use BrewSmith on my Mac to build recipes, track Inventory, Enter notes, etc. It's a bit busy but it does everything I need and then some including compensating for equipment and grain temps, loss to HLT/MLT/BK and hose volumes.
I only use iBrewMaster on brew day because it's easy to carry around from the basement to the garage as I'm assembling ingredients and starting/stopping timers.