The year in guitar effects has been pretty mild, with the exception of the Digitech iStomp.  In my opinion, this is a pretty big shift in the world of the traditional stomp box.  Unlike Digitech's earlier foray into the iOS space with the iPad-based IPB-10, the iStomp is practical and affordable (besides being cool.)

Out of the Box

The first impressive aspect of the iStomp is the slim form.  This thing is about the size of two iphones stacked on top of each other.  Not bad for a pedal that can do so much. The idea of the iStomp is that you can assign the pedal to be any effect.  You do this by downloading pedals using the free iStomp iOS app.  The app comes with a few pedals, and more are available for purchase, at about $5 each.  One day you want it to be a classic overdrive?  Just push it out using the included iOS to pedal cable.  Tomorrow you want a delay?  Just load it up.
The pedal is super intuitive to use.  You plug it into your iOS device, and it is quickly recognized and prompts you for authorization.  Once you select the pedal you want to assign, hit the load icon.  30 seconds later you have a fancy pants pedal.
The first time I connected everything, I received an error message and had to reset the pedal and the app.  After that everything worked flawlessly.  Utilizing good product design, the error message told me that's what I had to do to get things working. The four knobs on the device are dynamically assigned based on what pedal you select.  That can be a bit awkward, as the nobs have different functions.  Your delay decay might be cranked up, but when you switch to a tube overdrive pedal, that is suddenly your master level knob.  So, watch out for that.  In the past Digitech devices keep the levels at a default moderate level until you start using the knob- (I know my GNX board and J-Station are this way).  But on the iStomp, if the knob is cranked, that function is cranked as soon as you load it up and kick it on. But, quick switching between pedals is not what this is designed for.

What the iStomp is:

A very versatile pedal Perhaps the last standalone stomp box you will need to buy

What the iStomp is not:

It is not a multi-effects pedal.  You get one pedal at a time It is not designed for quick switching.  Don't expect to have your phone out at a gig and quickly flip between presets.  It takes 30 seconds to load a new profile, so it is really designed to be set and forgotten about.

Overall Opinion

Its a great value at about $150.  Add another $10 or $20 in pedals through the app purchases, and you will have a nice little collection.  It is practical and convenient. Check out the iStomp here.