I love this color! My wife wanted me to pick up a bottle, and I'm glad I did. It is a shade of green that reminds me of freshly-cut grass in the springtime, really "cheery" to look at. It flows exceedingly well, in a really wet nib it could be a little like a firehose. The upshot of that is it's really fun to watch it pool and move around while you're writing, and I don't have problems with feathering and dry time so there seems to be no ill effects there.
Vert Olive vs Vert Pre: I haven't inked up with Pre yet, but I did grab my wife's Pelikan and write for a bit on different papers to see what I think. I just so happened to have my m800 inked up with Vert Olive at the same time, and wrote some text in the back of my Moleskine where I keep color tests to see how they compared. The colors are really quite different; the Vert pre is actually a little easier to read in the Moleskine because it really pops off the page. Vert Pre flows much more easily than Olive, which even in my fairly wet m800 doesn't flow as silky smooth as other Herbin's. To me, Pre has a "modern" look to it; rather bright and cheery vs. the Olive's sortof "vintage dirty olive green" color. I guess that sums it up for me:
Vert Pre: "cheery" flowing lots of fun
Vert Olive: "moody" vintage and more serious.
I hope that helps.
Thanks for posting the review, I think this will be a fun color once Spring hits. Or maybe Springtime of the mind

Edit: I forgot to add that in real life, Vert Pre looks more lime-y to me than this scan shows. It's a bit lighter and brighter. Could be my bottle is a little different, or maybe the scan isn't quite showing this characteristic well.