The standard filter is pretty good kit. It is well made and well packaged, at a price which will take some beating. It is also very versatile. This is a complete system, not just a straw, so is one filter that should be on any back packers 'consideration' list.
The filter may be used to take water from rivers, lakes, public fountains and even muddy puddles, so just about universal in this respect.
In use, as per normal advice, it should be really only be used when the water source is clear and running if possible. The worse the water, the quicker the filter will clog.
Having said that, I have used this filter in some filthy water. It tasted very clean, like the best quality cold, bottled water, with a good flow rate. However, the water was still cloudy, so you would not want to cook in the stuff, unless brought to a boil first. If adding to dry rations, it may put a few people off, which is why a clear water source is desirable. Having said this, the filter does take out the nasties in any water, so in an emergency, this filter can be used with confidences.
No virus groups can be totally eliminated by just filtering. These come in at around 0.004 microns, so a filter of 0.01 microns will have no effect. This is usually not a problem, but if the user is concerned, then boiling, chemical tablets or a uv pen will solve the problem.
Thus this filter is a very good performer, light weight and for the price, worthy of consideration by any traveler.