I have an iphone 3gs which i have a ton of apps on but barely use any besides ebay/weather/paypal and safari. I have been playing the AH recently to save tons of gold for Catalysm and now I see this new app for the Auction House.
Why should I spend $3 a month to use the AH? It's not like getting to the AH is hard. In-fact using the touch screen is a lot slower when I am listing a lot of items. Why would I want to spend my lunch break posting auctions from work on my phone when I could just come home and do it faster without wasting my hour break and not wasting more money on the game.
If anything blizzard should pay me the $3 a month to use the app over logging ingame to do it faster/easier. Less people logging in = less bandwidth for blizzards server therefore they pay less to run servers etc.