ISUK:

The Mclaren base price in the UK is less than the 458 but a lot of the standard fit kit on the 458 is not standard on the MP4 .... CCB's for starters. When you add back the items missing from the Mclaren that are standard on the 458 it becomes a more expensive car.

 Is a standard MP4 (without the things that are standard in the Ferrari) just as good or better than a standard 458? I think that is the real comparison on a performance level. The dealer and maintenance situation is something that the first batch of owners will have to deal with just for having the privilege of being amongst the first while McL establish themselves  in the market and build a more effective network.