Here's some detailed description[1] of New Horizon's science payload. Also technical details link on the bottom of the page. I guess not all the information is in the form of a layman (like me too) asking "just how good they are?", so might need some "science->masses" translation.

There's also a writeup on ArXiv[2], that seems to be even more detailed, though just found it and skimmed so far.

[1]: http://pluto.jhuapl.edu/Mission/Spacecraft/Payload.php

[2]: http://arxiv.org/abs/0709.4261