I have one and use it a lot with my SS amp - not too bad for the $$$. Presets need tweaking but then all presets usually do. Doesn't sound that good with my tube amps though. Best $99 I've spent in the past 2 years.
Now running an Eleven Rack with Pro Tools 10.3.3 - it's amazing and I'm having ball with it - worth every penny. PT 10 is tops IMO and the Eleven Rack is a work of art!

I have a G2.1u, basically the same as the G2 but with an expression pedal. It sounds okay in the house, but in a live environment... it sounds pretty naff.

To be fair, some of the phaser, flanger and delay effects are pretty decent, but the wah and distortion are crap. To put it nicely.

There is worse than the G2, but I wouldn't recommend it.
Got on the bus with me daysavaaaa
It's good for playing around with effects and learning how they work, but sound quality isn't great. It's a shame mine broke...it was good for quiet practice with a set of headphones.
i got a boss me20 for about £120 and it really boosted my tone, the effects are good, but better from real expression pedals

But everything can be tweaked to sound better

I can't sing its praises higher than that
Its one of the better sounding multieffects. I wouldn't buy one for distortion anyway, and as said the phaser, flanger, etc. is pretty good. This is from a multieffects hater. I would never use one of these things for gigging.
for what it is and how much it costs, it does a pretty good job. i have two recordings in my profile, one is with a zoom g2, the other is with a line 6 pod XT. you can definitely tell which is which, but the Zoom held up decently
Grammar and spelling omitted as an exercise for the reader.
i've just sold mine but i thought it was one of the bst multi effects i have played. the effects part of the unit are where it shines with all of the distortion models being poor.

seriously though if you just want something cheap but excellent value for money and great effects the g2 will be your best bet. it beats all korgs i have tried for effects but not for distortion