hand helds (in my experiance) are ok for short term use for groups of 1-3. but they are not sturdy and when people are using them all day long they WILL fail.
i like the above filter, use it for larger groups on river trips. its a good idea to pre-filter and put the cleanest water you can find/make in. it makes a huge difference.
good ole bleach or iodine works a s well.