Really Epic

I got the Boss PS-6 Harmonist for Christmas last year, and all I can say is that I'm blown away from how amazing it can be. With all of the effects I can put into my guitar now, it sounds amazing! Plus, it doesn't take the great sound away from a Marshall or a Vox amp. If you get this for a holiday or your birthday, take it from me, you will absolutely love it!

My 2nd favorite Boss pedal...

like any new pedal with multiple functions, it took me awhile to get used to this pedal, but now that i have it's become my 2nd favorite Boss pedal (only behind the legendary, but discontinued, DD-5)

the harmonies are amazing (as long as you have the settings right) and as long as they are used tastefully, it can add alot to make a passage sound more full.

the detune option is a great 80's era chorus effect (think Enter Sandman introduction). I don't have a chorus on my board, so whenever i need one this fills the role perfectly.

My favorite option is the Superbend. I can now get crazy whammy-esque effects for my stop-tail guitars, and setting the rise and fall knobs to the max provides some really fun noises.

Boss pedals have a reputation of either being amazing or leaving alot to be desired... in this case, they knocked the ball out of the park with this one!

Get's the job done

It's the best Harmonist considering price and features.
I believe Boss have improved the user interface to make it easier than it's predecessor and also added some other cool features like pitch shift (by pressing and releasing the pedal).
As with many other harmonist effects, there will be some limitations and your overall sound will depend much on the place where you put this on the effect chain.
When using it with an overdrive or distorion, the distortion quality will have a dramatic influence on the harmonist sound (depending on the direct and effect level mix). I use this with a Fulltone OCD and sometimes with the Ibanez Tube Screamer and get very nice sounds with those combinations.