Quality gear

Haven't had time to put this through all the paces but I'm very pleased with what I've used so far. Great build quality and it delivers terrific tone. Some of the presets could have been omitted (can't imagine a practical use) but some are very tasty. Terrific variety of amp models and FX. The assortment of jacks on the back of the unit fit nearly every possible need and the looper is a very nice add-on. So far I'm a very satisfied customer.

HD amp modeling is great

Was never much of a Line6 fan until i bought the PodHD400. The podHD400 changed my mind immediately. Found my tone very quickly and it sounded great through a marshall half stack. Great distortion tones, especially the tube screamer, and great clean tones. Sounds even better through my new line6 DT50 amp. Integration is awesome. Also, a boss ge-7 eq pedal sounds REALLY good paired with this.

Powerful and Convincing

An amazing number of good to great quality amp/cab models, effects, and other tweaks (pre/post switch, model in-out, different cab-mike emulations, etc.) give this an infinite number of possibilities, and with the editing software, it's relatively easy to configure a couple of banks of patches that will give you a tremendous range of tones without complex or lengthy pedal button antics.

The ability to switch 3 effects in/out, within any patch, makes it suitable for many live situations, and reduce the number of patches you need to create.

I also use it for practice, and the patch editing software is very helpful. Not the best UI in the world, but it gets the job done. Trying to manually fiddle with all the settings is not as precise, and with the software it's easy to make minor changes and switch back and forth to fine tune the sound. Then, you can rearrange for easiest switching during performance.

The manual (PDF download) could be better.

Tech specs are totally absent. Very disappointing. Also, be aware that Line 6 does not support any headphones lower than 150 ohms. Some people have reported problems "normal" impedance phones. (I use an old set of Sony MDR V6's and they are a bit loud, but good quality, IMO.) If you plan to use this for practice, and have typical (~32Ohm) headphones that turn out to not sound good plugged into your POD HD, you will get NO help from Line 6, so be prepared to throw $200+ at phones they recommend.

Great HD Tones

Great amp models (16), FX (mods-delays-verbs) with many "tweakable" parameters. Made like a tank, laid out intelligently, and with every back-panel feature you would want for live/studio use. Maybe it was in an effort to be "green" or eco-friendly, but it only comes with a "Pilot's Guide" to understand the basic features. Buyers are invited to print their own 121-page Advanced User's Guide when a decent bound version could have been included in this package. That's the only drawback to this cost-effective alternative to Axe-FX and other rack units.