caffynz: I'm the type that likes to acknowledge decent customer service, especially when it's probably common for the company to receive complaints, or no feedback at all. Because I know what it's like to receive a few glowing compliments amongst many negative feedback. 

It's also good for customer service/support staff who get rated based on things like time spent with customers, i.e. where they're incentivised to close a ticket as quickly as possible.  Apart from giving them warm fuzzies, it also lets their Mgt. know that the time is well spent.  A few years ago a United Airlines person did such a fantastic job in dealing with a rewards booking that I wrote a (longish) email to their feedback address pointing out what a great job she'd done.  It took quite a few months but eventually I got an email back thanking me for letting them know.  I think the channels for praise, rather than complaints, are pretty minimal and clogged up, so things move quite slowly.