I seem to have fostered a reputation as an authority on 200GS (and below) so it's probably appropriate for me to contribute.
Unlike some who will be passing judgement on these lowly components, I currently have bikes built up with them. As such I've used them recently, so can perhaps offer an objective opinion based on the functionality of such kit compared with other groupsets throughout the range.
The differences between parts through the ranges are definitely incremental, with less pressed steel, tighter manufacturing tolerances and better pivot materials as you move way from the bottom towards the top.
In use these differences are often less obvious; at least at first.
Compare a well set up 200GS rear mech to a well set up XT rear mech and the shifting performance is actually quite similar. The thing is though that invariably the 200GS will lose it's indexing much more quickly due to the inherent 'sloppyness' in it's pivots.
Interestingly though, I've seen similar poor performance from a 'Paul's' rear mech when it gets muddy.
The rare 200GS thumbshifter with it's lightweight composite body (plastic) is comedically awful, whereas the XT thumbshifter is a thing of engineering excellence and beauty.
The 200GS chainset, with it's pressed steel chainrings, is so durable it hurts. Especially when you drop it on your foot whilst removing it from a bike. The 201GS chainset is less cruel to a bike as it has aluminium crank arms and replaceable rings.
The brakes are terrible too.
Back in 1992 when 200GS first appeared, I was riding XT and DX equipped bikes, but before that I was using some pretty low end stuff. I knew it was low end back then and aspired to better and 'cooler' components as and when I could afford them. But it never stopped me having great fun on whatever I was riding at the time, nor does it now.
So in summary, low end groupsets are definitely not cool at all. Which is probably why I kind of like them.