This kit contains the essentials for driving in Europe - with the addition of a reasonably handy AA book that gives some additional useful information like speed limits and toll road charges. Best of all the whole kit comes in a useful bag that you can store in the car. Works out cheaper than buying the individual component products although depending on where you are planning to drive, the first aid kit is not essential but nevertheless a useful thing to have. Highly recommended.
As an aside, some reviewers here commented on poor delivery. Of course this is the place to review the product rather than delivery but there are a number of vendors who supply this product through Amazon. I cannot comment on the others, but the cheapest when I bought mine was Tamar Shop - and delivery was excellent. Order dispatched that day and arrived two days later. Definitely best not to leave buying this to the day before you are planning to leave but if you use this supplier, I'd have no fears about delivery.
2012 Edit: Note that you now need to carry breathalyser kits in France too which are - or certainly were - not included in this kit. Also remember that although it's not part of the requirement, you really need two breathalysers - otherwise if you have one, use it, find you are OK to drive, you are suddenly illegal because you don't have a breathalyser! Vive la difference!