I have this bag in black and I love it. The only thing that annoys me about this bag is how inconvenient it is to open and close it. The leather is of good quality so I don't expect it to tear, rip, etc... The classic is fairly large, roughly the size of a large kooba hobo. If you are expecting a cute little tote, you're in for a surprise.
I would never see the Giselle as an investment since it has had its hayday a while ago. I don't think it will come back either since so many variations of the same bag has been made, so I would only purchase it if you love it.
The leather is very sturdy so I expect that to last. The white is very white so it will get dirty. If you are prone to abusing your bags, I would probably get it in another color. Other than that, It's a great fun bag, I love its lines. Just be sure you buy from a reputable person because there are loads of superfakes out there.
Good luck!