I've owned my C4 for five years now and have to say that it's virtually trouble free and 100% reliable. I've test driven newer Porsches with a view towards trading up but have resisted mainly because I'm not so sure it truely is a step up. For now, she's a keeper.
Power, wow factor. Gotta love the Guard's Red with Beige interior.
Better heating and ventilation. Ergonomics are somewhat questionable.