This is actually my *third* pair of WI-C100s- the first pair lasted a good several months (if not over a year) but the cable from the battery to the earbud came loose on one side; the second I lost on the way to work after months of use, probably while having to run for a bus or snagged on my backpack strap and fell off (was...not a good morning hah)So....yes, since they're so light they are easy to slip off accidentally if you don't have one or both ears in-use to keep it from running off your neck (mostly when running or leaning/laying back, basic day-to-day activities don't usually knock em loose ime) that's really the only "big" downside I've found so far across these- and I've been using this same model for a few years now. And worst case scenario, if you do lose em they're cheap and easy to replace, widely available- sometimes even at local stores (though my nearby places didn't this time around)Because they're tethered together, I don't have to worry about losing one ear because it fell out mid-use or I forgot to put it back into the case when not in use. Sometimes you may need to be careful using these when wearing any "cross-chest strap" bags or otherwise (messenger/gym/duffel bags, purses, arm-slings, tools with a neck/shoulder strap, etc) to make sure the earbuds don't get caught under the strap- but for the tradeoff of reliability and peace-of-mind of having them semi-wired, I don't mind that occasional snag too much. Even when they do lightly catch on my backpack strap, they haven't seemed to wear down or come loose around the wire at either end (the pair I had that *did* break in that way came loose at the battery end, and wasn't caused by a shoulder strap- was also after several months of heavy use, even while sleeping)So build quality is reasonable, how do they sound? Honestly, for a $20-30 pair of *wireless* earbuds, pretty decent ^-^ sure it may not satisfy any audiophiles, but again....don't forget the price- even for that, they still sound great to me (of course, that could just be Sony and their reasonable consistency/quality with even budget headphones over the years heh) and the extra features from the Sound Connect app are a nice bonus. Of course it's not going to have extra-thumpy bass (try their "XB" line of products for that) or Sennheiser/Bose/what-have-you quality- but the equalizer and DSEE do give you some extra control over how they sound. Oh, and you can also enable/disable the voice msgs from the app, so it'll only speak up when turning on/off the headset, and when the battery is lowThe connection consistency and quality have been pretty good across all 3 pairs I've had. For reference, I not only use them with my phone daily (close proximity, but also connecting to Android over BT often works better than with Windows) but also with my PC just as often- and I've never had a problem with initial pairing or swapping between the two. When in use with my PC, even when in another room several ft away they still maintain a good connection, only *rarely* drops out from far away if I move my arm in the way of the line-of-sight (granted, that may also be another advantage of the "pair on the same wire" style of headset over individual or TWS [true wireless sound, or "airpod style" with the separate batteries/bt connections per ear] buds- ymmv with your device(s) of choice)The battery life....hoo boy, they're not kidding when they say upwards of 20-25 hrs. Not only do these have a larger battery thanks to the type of headset- but also since the battery is along the band instead of the buds themselves, the earbuds are much lower profile and work great for wearing during sleep without having to worry about them falling out or losing charge too soon (as long as you don't mind the wires- but even then, they're pretty lightweight and unobtrusive) especially with the right eartips to help keep em snug and secure. Personally, with my living situation having something playing in my ears to drown out outside noise while sleeping was....a necessity- with some memory foam eartips (the included ones would normally be ok, but my inner ear is a bit wide even for the included large tips to work ._.) you almost don't need active noise-cancelling with these ^-^ speaking of eartips, the posts on these are also decently long unlike most TWS buds, so they have a bit more flexibility with options for those (one of my major problems with several TWS pairs I've tried)Between the long battery life (and decently fast charging speed, even over a PC USB instead of 2A wall adapter), comfortable wear, decent sound quality for price, and extra features in the companion app, I'm pretty happy with these as a daily driver(As for the provided eartips, there's nothing wrong with em and will likely work for most, I'm just a bit of an odd case with ear shape hah)