The ULA Amigo Pro uses the Katadyn Hiker Pro filter, so you can find out more about what it filters on the Katadyn site. Yes, it does filter bacteria as well as protozoa, but not viruses (normally viruses aren't a problem in the US).

I have the Amigo Pro and absolutely love it. I used to get horrible back spasms bending over the water source using a pump filter, so I really appreciate the Amigo Pro. If you want to filter water during the day, just fill the bag about half full and connect it to your 1-liter Platypus bottle (helps if you have the Platypus filter connector). Do this at the beginning of your rest stop and you'll get much more rest than if you were pumping! You do have to keep an occasional eye on it, though. The bottle you're filtering into could overflow or tip over. WIth Platypud bottles and the connector, about halfway through the air inside gets so compressed that it stops the flow. I haven't had any problems with the Platy bottles blowing up (yet), but you do have to undo the cap and "burp" the air out of the bottle a couple of times. So I wouldn't leave the Amigo Pro completely alone to gather wood, but you can admire the scenery, set up your shelter or start your dinner while it's filtering.

It does take a little practice to learn how to fill the "bucket" (does require getting one hand wet) and to carry it to your camp site without spilling it (into your boots, of course). Once you've figured it out, though, no problems.

The main problem with the Amigo Pro is on the rare occasions when there isn't anything handy from which to hang the filter. On one occasion, I had to sit and hold the thing up, which was really good to strengthen arm muscles but was rather tiring. If you're getting water from something other than a rapidly flowing stream, you'll have to dip with your cooking pot. Since the "bucket" for the Amigo Pro is a circular of silnylon with drawstrings, it takes some practice to do this since when you pull on the drawstrings the top closes completely. If I were going to improve the design, I would make a shaped bucket instead of the circular piece of silnylon so that when you pull up on the handles the top is still open enough to pour water into.

Unless I suspect the water source is horribly contaminated (say, a river downstream of human settlement), I would never use chemicals in conjunction with the Amigo Pro. Having had a horrible experience (severe allergic reactions) with iodine, I try to avoid use of any chemicals. However, I always carry a couple days' worth of Katadyn MicroPur (chlorine dioxide) tablets as backup just in case something happens to the filter. If you pull the filter to use the thing as a shower, you want to either to run through some chlorine dioxide or boil the output hose, because you'll have contaminated it. The same thing will happen if you drop the output hose into the water source (I've done this with the Amigo as well as with pump filters several times.