Hard for me to compare because I only have the v-amp2 and never played with the gen 3. My recommendation for you is this : if you play in your basement at low volume (I mean without a band) and you wont be moving the unit around, then, go buy it. Otherwise, don't; you will not be happy with it.
All plastic made except for the
foot switch casing, the plugs gets loose quickly, the distortion feels VERY digital, the rubber of the power cord is so dry and cheap that it's still folded and twisted just like the day I took it out of the box. There's no on/off switch; you need to unplug. And the worst thing ; after 6 months or so, you will loose all your custom settings because the battery will die and you will have to perform a micro-surgery to replace it.

Other than all that, it's a nice device with nice clean sounds.
I would go with gen3 or anything else for that matter but that is just my own personnal opinion.
Cheers,
Mathieu Bourgon
mathieu.bourgon@videotron.ca