I'm not all that impressed. Not to say its not damned cool, but the major downfall of the M16 is that damned 5.56 (That and the gas system).
If you REALLY want a good gun go with a 6.8 SPC in an M16 platform that has been modified to use the AK gas system. That would be a combat rifle.
The M16 comes in all different flavors and styles, and most are interchangable.