My biggest concern is that this will be another thing to fiddle with and charge for. I'm happy to report that after a single charge and regular use, it's been 6 weeks and it still shows a full charge. This is not a scientific instrument. If you need +/- 1psi accuracy then this tool is not for you. But I just wanted to know if my tire was flat from a puncture and they're pretty good for that. My biggest complaint is that the device doesn't have a "heartbeat" sensor to show how old the reading is. . There were times when it was fairly obvious (due to a temperature/pressure jump) that the information displayed was being saved from old readings. This can be problematic. However, in my tests so far, it seems like the update happens within 60 seconds of making changes, which is more than enough for me. I'm afraid that if something happens to the sensor and it doesn't send updated information, there's no way of knowing that the display is old information. However, during my ride, the temperature and pressure change so much that I think I would notice. A heartbeat/update indicator would be a nice addition. Update: I bought my first device over a year ago. And since the rating is up, there are about two more, for a total of six. Zero problems so far. I live in Seattle and they have no problem with rain. Amazing battery life! The best product on the market. One of the head units I bought for my girlfriend's bike was either stolen or dropped. I contacted the company and they charged me a fair price for a new head unit and sent me instructions on how to pair it with their existing sensors, which saved us a few bucks. Problem when the main unit shows very old information. This usually corrects itself within a few seconds after a ride. But I always wonder what happens when one of the valve sensors dies. But so far I haven't had to touch them. To answer some of the other reviews, I haven't had any issues with them leaking or the tires needing to be pumped up. Tighten them up.