I know it's been out for a while, but I just got one (for a rather striking price).
The POD HD is a wonderfully versatile amp modeller and multi-effects processor. In this new HD guise the amp models have been completely revamped to have a much more natural break up and dynamic response to your playing.
The effects too, have been upgraded and are now "M Class" effects, meaning that they are equivalent to the effects in Line 6's M series multi effects units, which are held in high esteem.
On the surface the POD HD is a simple beast, with effects and amp models, and direct control over all of the parameters the same way you'd have control over them if you were to have the real things in front of you. But when you delve deeper into the settings you can change quite a lot more. You have complete control over all of the input and output settings, allowing you to match things with your recording hardware.It should prove to be an invaluable studio tool for tracking guitars and re-amping through the models.
