Pros:
Three modes. 85, 60, and 40 (approx)lumens.
Four C-Cell batteries for great runtime.
Lighter (less heavy) than my 2C mag-light.
Very good side spill with non-overpowering hot spot.
Cree Led.
Easily modded with plenty of room to spare.
OP Reflector for smoother beam.
Very white semi warm tint.
Very good grip
Reflector is held on by an actual ring nut (good).
Supports NI-MHs.
Cons:
Could be brighter for a flashlight on 6vdc.
Certain brands of alkaline batteries are a bit loose in the barrel.
Looks like Type 1 or better anodizing on the barrel.
The aluminum head is coated in thick durable plastic (Pro or Con?).
Plastic outer lens.
Switch is a tad annoying as it's a simple electronic depress cap type of switch.
Not regualted except for resistance via the mode switching. Otherwise direct drive.
Other Thoughts:
This flashlight might seem long. However it's significantly shorter than it's mag-lite counterpart. Not to mention lighter and has a much more useful beam.
Between it's predecessor with a smooth reflector . The 504c is a much better deal.
Bottomline:
I would recomend this as a good replacement for a mag-lite.