I'm also wondering what the effect of driver error is going to be. Imaging getting the wrong setting/forgetting to change/or failure at the end of a main straight - it wouldn't be fun entering a corner with no front-end downforce; 2.4L, 700+bhp, 200mph, brown trousers.
*LOL* I must admit I'm enjoying MotoGP more these days, as there's much more overtaking than F1.
It has surprised me that more hasn't been done about the problems of following another car. On the UK TV coverage they did an article a couple of years back showing the level of restrictions on the designers - basically, a set of volumes are prescribed, and the specified elements (front wing, cockpit, sidepods etc.) of the car must fit into the specified volumes. Hence why some people criticise the cars for looking so similar.
If they're that controlled, I would've thought they could specify that a volume of space behind the car must be 'clean' to a certain level. I.e. you can do what you want to increase downforce, but you mustn't damage the air for the guy behind. Perhaps it's not that simple (I don't have a degree in aerodynamics)!