I have taken this exclusively in the Whites of New Hampshire for a year now on at least 8 or so trips, so it's seen some use.
You should assume that no illness has come from using this, or I wouldn't have given it 5 stars, so I will write about the other features that make this a nice system.
Aside from it's relatively light weight, it packs small and is very easy to set up--just attach the intake and outtake and you are done. Pumping action is smooth and without much tension, so you can filter at a fast rate which is handy when you are filling up for 3 or 4 people. It's very easy to clean, requiring nothing more than a short run with water and a little bleach when you get home.
When the filter has had it, you will notice it becoming harder to pump. Once that filter is clogged, it will need replacing. Filters are around $40, and this is the one downside to it, but I'm on a year without replacement yet. I think so long as you are not filtering heavily dirty water you should get a good life out of it.
Overall, its easy to use and fast, and will provide you with quick, clean water ready to drink. Attach a charcoal filter to it if you want to improve the flavor and filter other impurities.