I got my m400 as a Christmas gift from my husband and have used it religiously since. I researched running and activity tracking watching for a few month before hand and decided I would save for this one. Instead I ended up getting it as a gift and was thrilled. I thought I had made the right decision in my research, but now Im not so sure. The watch and iPhone app used to work seamlessly and I really enjoyed the ease of use within the app. Since Polars update, I cannot sync. It takes several unsuccessful attempts to finally connect to my iPhone. Once connected, it takes what feels like eons to successfully sync all the information from my watch. I mean FOREVER compared to how quickly it used to sync. Im not a fan of the interface change that came with the update either. Some features that I liked have disappeared-like someone else mentioned, the weight tracker. I could get used to it though if I wasnt so frustrated with the inability to sync. Since the initial update and change I saw that Polar released another update. Under the update it said it was to "fix bugs." Clearly, they have not figured out after all of the reviews that this bug should be a priority to fix! Its a bummer when you spend a good chunk of money on a product and it doesnt do what its supposed. I know I didnt spend the money, but someone I care about wasted their money on a gift for me. I hope Polar gets their act together before all of us switch to a Garmin or something.