The first thing woudl bother me. I like the idea of using my smartphone charger plugged into my wall or PC to charge my controller, because I don't know that the cable will be long enough to get from my console to my controller. If you don't HAVE rechargeable batteries anywhere (read: they got lost), I'd spend the money on the Play & Charge over new batteries myself.
Well, I checked the prices and it seems you can get 4 rechargeable batteries and the charger for 25-30 euros or so. At least around here, most places seem to sell it the play & charge kit for 35€ or so and this would only really cover one of the controller for me. Although early on there wont be much if any split screen co-ops that I would likely play and if there was, I could for the occasion use normal batteries for the second controller.
Hmh, it seems the US Xbox-site lists the play&charge kit at 25usd, which would be like 20 euros or something.. I suppose there is nothing regional about these and I could get this stuff abroad for cheaper..
EDIT: Charging cable in the charger-kit is 9 foot/2,7m long.
I guess at 25€ or so it would be worth it over rechargeable batteries.. gotta keep my eyes peeled.