I looked through the albums and listened to some of the ones I didn't hear from bands I find ok to very good. I didn't listen to the LatAm artists. I'm unfamiliar with those artists normal work.

Key Takeaways:

Nirvana was the best of the lot.
The hiphop was really badly executed in this format overall with the exception of Lauren Hill. Still prefer the album versions of songs.
Maxwell's cover of NIN's closer is odd. NIN music is closer to funk than most people realize but he chose to cover a track that is not funky at all. Daring move.
MTV should have targetted indie bands instead of the washed up corporate rock bands they padded the episodes with.
MTV Unplugged is very plugged. Every band/artist used at least one or all of electric bass, digital reverb, or backing tracks. This is the nature of live sound. These things are never purely acoustic.
How you gonna do an acoustic "Can I kick it?" without an upright bass???? That would have sounded great. At least it was acoustic.
The Police suck. Eric Clapton is boring as a solo artist. Fuck Kiss.
Rod Stewart should have done "Do ya think I'm sexy". Boring.
Korn...was...ok? Amy Lee has a wonderful voice. No Auto-tune warble on her vox*. I wouldn't go out of my way to listen to Korn but I would not be annoyed by this album if it was on.

I would say for the most part the "plugged" in versions are better but there are a few surprises.

I heard light auto-tune on some of the post 03 stuff. They actually used the rack auto-tune at first and you can sort of tell with light warble on the higher frequencies being more apparent. It was a common limitation in the early hardware. I though I heard some in the Florence and the Machines set too but I could be wrong.