I agree. I have an old Platypus Sweetwater filter, the same filter now owned and sold by MSR. It works pretty good. Filters let you pump out of very shallow pools without stirring up sediment, where dipping with a water bottle or bladder may be difficult or impossible.

When I need to save weight (BP/hiking) and I know the area and the availability/quality of it's water sources, I go with chemical purification tablets - either Potable Aqua (iodine), available at most Wal-marts, or Mcnett Aquamira (ClO2). Aquamira is more effective at killing microorganisms than iodine, but it's hard to find, costs 4X as much and has a shorter shelf life. Tastes a bit like swimming pool water too, I prefer the taste of iodine.

I have occasionally got a little sick (diarrhea, nausea, fever) from "bad" water using both filtration and chemical (and even combined) treatments. Neither is 100% effective in some places. The only method that has never let me down is 5" of rolling boil. Also, drinking ground water in an area where livestock graze is evidently a bad idea, avoid if at all possible.

Oops. I just read Avatarworf's link (same filter) - my experience is the same. And as others have pointed out, you can just carry a helluva lot of water if you anticipate no supply.