Hi, I have bags from 2005, 06, 07, 08, and 09. My bags are being used in extreme weather of hot, hot, hot and very strong sun light, and the other extreme, cold, clod, cold Finnish winter. IMO the bags hold well, but some of the colours are less lasting than the others, and some colours fade fairly quickly. I have been using LMB products to prevent any damage to bags, and most of them are still as new, because I take really meticulously care of them.
My 07 Chevre bags seem to hold better than the newer ones. Colour that fade kind of quickly without really good care are semi light blues and pinks, white ones need good care not to get dirty, and corners of bags are always in danger to become scuffed.
I would say, that use your bag and take care of it with good cleanser, conditioner and shine enhancer, and you should be good.
I have owned bags ranging from 2003, 2005, 2007, 2008, and 2009 and I agree with Aarponen. I would add that black Balenciaga bags tend to fade over time to a greyish or greenish color. Also, the bags show scratches fairly easily, so keep your nails filed and take care not to brush against anything when you're out and about. Balenciaga bags are not tough like LV bags, for example. But they are far more beautiful!
my older bags don't have as many scratches as my newer bags do... not sure if it's the finish or the color, but the older ones have held up really well. the newer seasons that i have tend to show the scratches easier and the leather color is known to fade. i wish bal made bags like they use to! when i use my bags, i'll use them for months at a time without trading out... they're just so comfortable and easy to use!