I've had only one issue with them, in that the inside has become scratched and discoloured, which somehow messes up the taste as well (after about 2 years use).
A totally worth-while purchase. I'm now on my second one, hopefully this lasts longer, but if not, I'll just buy another one in a couple years.
One thing I like is how manual the process is - I can make a much weaker cup of coffee for guests who don't like it so strong without it becoming bitter. For different types of coffee, I can brew it in different ways.
And it's odd, but even cheap pre-ground supermarket coffee tastes hugely nicer with the AP. These days, I buy pretty much whichever the cheapest fairtrade coffeebeans the supermarket has, and grind enough for each cup, and it tastes great.