It is ****** expensive (and gives some indication of why Nav costs so much in Audi's with the included TMC lifetime subscription), but I've been across to mainland Europe 3 times in the car this year, and when it blue screened on me in the middle of Strasbourg I'd have happily paid £150 for an immediate solution! They're usually much more than that, so I thought I would buy one whilst it was on offer. The 2009 copy I'd purchased for £20 hunts constantly, and the risk is it will knacker the RNS-E optical reader mechanism if it is worked too hard.
Fair to say it is very pricey, but I think it did add some very basic functionality enhancements to the mapping, although the Swindon bypass to Cheltenham which has been built since 2008 still isn't accurately mapped!