Lots of different pedals, amps, and other sound effects inside of the unit to approximate a certain sound you'd like. Highly functional- especially the tuner that's included. It can be overwhelming at first but after a few rounds of noodling around with the unit, it becomes intuitive to use. Great for studio work.
Second generation of Line 6's modeling solution Pretty versatile to get a lot of basic amp sounds. Some effects are workable, some sound clearly digital. It's really picky about its voltage.
The screen no longer works, but I run the aux outs of my Ion into the Pod XT so I can mix the wet/dry signal manually live, rolling in the distortion when needed.