I am trying to trade some items on CraigsList. Someone has offered me a Zoom g2.1u effects pedal. Does anyone have experience with one of these? Any thoughts or commentary on the sound quality/durability/value of these? I have an '80s Fender Strat HH, a Gibson Les Paul and a Carvin x100b.

Some possible advantages of the item: many different distortions and effects and it can be used as a recording interface. I would only be using this for working on music at home (non-professionally) and for practice.
When I first started playing I got one of these. Multi effects pedals are great, and of all the ones I have tried the zoom is one of the best. For practicing it's great, you could just hook up headphones to it and go.

As good as it is, it's still a digital multi effects pedal.

As for value, just look at what it goes for at dealers like guitar center and such. One problem I had with mine is after so long the expression pedal started getting really stiff.
Lots of pedals.
The distortion on it SUCKS. Chorus/reverb/delay is alright though...but I'll say it again:
I always found these to be very meh. The presets suck and I found it hard to program as well. TBH, with your rig it'd probably be a massive negative effect on your tone.
My band
PBT Native: Resident Graphics Monkey

Like I keep saying I only used it with a modelling amp so I can't really tell you how it really sounds but its a good wee multi fx although I wouldn't really recommend it for live use. If you want something cheap then go for it but if not...
Tokai Love Rock
Vox AC4
Danelectro Transparent Overdrive
T.C. Electronic Nova Repeater
Stomp Under Foot Violet Rams Head