For - works on Nokia E75, just put the card in the phone it installs & goes, covers whole of Europe, mapping seems OK, its fairly cheap + no ongoing costs, can lend card to friends if they need to navigate, uses internal GPS fine
Against - 2GB card has very little space left on it & you can't transfer to a bigger card so either lose most of your storage or have to carry 2 cards etc.
Biggest problem is will not connect to Garmin server so do not get POI, traffic etc. etc which was why I bought it. Garmin tech support are no help at all promise to ring back & don't as such can't really recommend this product