I really enjoy my 24oz Grayl GeoPress water bottle. I recently used it during an elk hunt in Montana.
I mostly used it in a running creek, but I also used it in an area where elk watered at, so there was feces and urine in the area I got my water from and the purification filter did its job, water was good and fresh.
Initially the only negative I had was how hard it was to press the filter through the water but I soon learned to just use my body weight instead of trying to force it, and it wasn't such a big deal.
Hopefully the company will get another shipment of replaceable filters in...I have tried ordering them for over a year now and they are never on-hand.
Overall, really good product, I have 3 now.