Well I've had a couple.
I had an Allerhand messenger bag that was about average price and it lasted a couple of years - but it did get travelled with all over the country and has been overseas. It got used to death but the lining has come away from the inside and it's hard to clean.

I got an Oioi bag with DS and while it is beautifully crafted and will certainly last a while, I have to say it doesn't get used much.
I hate the compartments as like one of the PPs said it all gets jumbled anyway, and just irritates me.
I only take it when we travel (so a fair bit) or out the whole day (rare).

Usually I'm just a fan of a canvas tote, which cost pittance.
I don't do the handbag thang often so maybe that's why I'm none to keen to tote a huge bag around.

So that doesn't really help you does it. I mean i think 'nappy bags' are a great idea in theory, but it's a highly overrated concept for me and I won't be spending big $$$ on another one.