After using this to pump outside of the house for 1 week now, I'm really happy with this purchase. I have pumped at work, in the car, and on a plane with it and would 100% buy again. At first use, I wasn't sure about it compared to the S1--the massage function felt weak and I wasn't used to the single control that manipulates both speed and suction on expression mode (the higher the suction the slower the speed). However, I stuck with it and quickly realized that even though it doesn't feel as powerful as the S1 that I am used to, this pump works really well. I get the same volumes as I do with S1 in about the same time pumping. It is definitely a little bit louder than the S1 but it doesn't bother me (and again, was able to pump on the plane without attracting attention). Charge lasts >3-4 pump sessions. Note: I have tried elvies and much prefer this. I think the elvie parts are too cumbersome and more difficult to fridge hack. This pump uses all the same S1 parts that I already had (including charger, so I leave one at home and one at work), so now I have multiple flanges and valves that work for both pumps. Size is amazing--so much easier to travel with than my s1 and fits in the outside pocket of my sarah wells pumparoo bag. Overall, a definite win!