This is the best sweatband i've found so far!  The sweat channel works well, and does a good job of pushing the sweat away from my glasses towards the sides of my face.  I sweat like an absolute pig while mountain biking, so it comes in handy not having to clean my glasses every mile.  The Halo II holds plenty of sweat, as can be proven if you wring it out here and there when you stop.  It seems high quality and has held up well through its first 20 uses.

The Halo II is stretch like a standard headband instead of the original that uses a bandana style tie in the back.  I prefer the stretch because it fits better under my helmet.  At first I was skeptical and thought it might be tight and itchy but it isn't.  It actually conforms and I forget its there as soon as it absorbs the slightest bit of moisture.  I got white so it would blend in with my helmet, but the white is kind of vivid at first.  Of course it was dirty looking after the first use and dull like I expected.  If you care about looks you might want to get a dark color.

Now on to the only reason it didn't get the perfect 5/5 stars.  When you look down while wearing the band, the sweat will pour down onto whatever you are looking at.  For example, you look straight down at your map while wearing it soaked with sweat.. and you can kiss that non-waterproof map goodbye.  I stopped to adjust my caliper here and there only to get irritated with the sweat pouring down onto my caliper while I tweaked it.  Simple solution, whenever you stop to look at a map or something.. wring it out quick and put it back on.  Also keep in mind that you don't want to wring it out while wearing gloves... i've unfortunately been there..