There are so many different Bible applications for the iPad that I don't hope to even list them all. I certainly won't be trying all of them. One I am trying out right now is called "YouVersion". It can be used on the web or on many different devices. There are apps for the iPhone, iPad, Blackberry, Android, Windows Phone, HP Web OS, Java, Symbian and Mobile Web. One can read the ASV, AMP, CEB, CEV, CPDV, Douay, ESV, GNT (with or without deuterocanonicals), GWT, HCSB, KJV, LEB, MSG, NASB, NCV, NET, NIV, NIV (1984), NIV-UK, NLT, OJB, TNIV and WEB. Many of these are available to download for offline use. All the above versions are available whenever your device has web access (3G, Wifi, etc). The NIV, NIV 1984, NLT and TNIV can only be used online.
I tend toward pretty basic Bible use. I want to be able to look up a passage and read through whole books easily. I don't usually use the notes or book mark features. My goal with devices and their apps is that I can carry more versions than I could in paper. I use the iPad to supplement, not replace, my paper Bible. If I cannot quickly get to a verse in a particular application then I won't use it.
Reading straight through is fairly easy. Tapping left and right arrows on the screen move from one chapter to the next (and back). Swiping the screen up and down moves through the chapter itself. Jumping to a verse is easy as well. One tap brings up a scrolling list of books. Tap the book and a nice large chapter matrix appears. Tap the chapter and the verse matrix appears. Tap the verse and you're there. I found the larger numbers helped my clumsy fingers.
I should add that right now I am only downloading/using free Bible applications. YouVersion is free to use. Registration is required to download versions and is also free.