MSR market the Trailshot as a lightweight alternative to often bulky and heavy water filters. It's designed to be stashed in a pocket and deployed quickly.
You can use the Trailshot to drink directly from the source, much as you would with a Lifestraw, just pop the end of the hose into the water source and pump the water straight into your mouth. This gives you an instant hit of hydration making it ideal for fast and light activities. The hose is a decent length which means that you don't have to get your face right into the water source like you would with a Lifestraw, it also adds the flexibility to collect water from exactly the right spot rather than relying on flow to fill up a container.
The other option at your disposal is to pump water directly into a water bottle or hydration bladder. It takes a good few pumps (around 40) to fill a Hydroflask 18oz bottle but on balance it's a much quicker option than fiddling around with a filter that you have to assemble or worse still, one that's buried at the bottom of your pack.
Backflushing is easy and doesn't require any additional tools, you simply half fill the filter, give it a shake and release the water.
The filter fits into the pocket of your average outdoor jacket but it feels a bit clumsy there so is best stored in the hipbelt pocket of your pack or in a hydration belt. If you're going to store it elsewhere be assured that it takes up very little space.
At 142g it's impressively light considering that it could be used to supply the water needs of a small group if needed, the lightest comparable filter on the market is the Sawyer Squeeze which comes in a few grams lighter but in our opinion isn't quite as polished.
Overall, we found the Trailshot to be completely fuss-free to use and it surprised us with how well it performed in the field, it's also an absolute steal at £36 so comes highly recommended.