I have one that I have used on a couple of trips now. So far, I really like it. The convenience factor is very high on this device - pull it out and fill up a water bottle anywhere. The hand pump action isn't tiring, and you can fill a couple of bottles in no time.
Better yet, I have been using it in gravity mode with the dirty bag from my Platypus Gravity works system, and I filter directly into my 3L hydration bladder. The weight and volume of the Platypus dirty bag is negligible, so I think I have found a winner for a system - it does both on-the-fly trail filtering and gravity filtering in camp.
A word of caution - be SURE to clean the filter after every use. It seems less robust to sediment buildup than my Platypus filter. I backwash and/or use the MSR "shake" method to clean the filter EVERY time I use it, which is low effort and definitely worth it.