I've been using it almost daily for 20 minutes to 2 hours for almost 1 1/2 years now.SOUND: It sounds almost as good as a full blown stereo system, if not better depending on the stereo. The only thing that makes an actual stereo a little better is the fact the speakers aren't combined into one unit and the sound comes from multiple directions (but I'm tempted to get a 2nd one to fix that).The sub-woofers on the sides of this pack a significant punch at medium to high volumes, but still improve the sound even at low volumes. The sound is very full and never sounds "tinny" or even flat like smaller speakers usually do.It's stereo. I feel like I shouldn't have to mention this, but I do because the newer one isn't...BUILD QUALITY: The build quality is outstanding with almost no wear and tear even after a year of daily use and moving it around semi-frequently. The only real wear is a two or three hairline scratches where I slide it in and out of multiple times a day and honestly the fact it remained that way and isn't all scuffed up like I expected is amazing.The charging port door doesn't seem like it'll wear out anytime soon, nor do the jacks seem worn at all. I swing the thing by its carrying cord all the time and haven't seen any scratching or wear as a result and I have full confidence nothing bad will happen from doing so.BATTERY: The battery life for me was about 2 weeks when I got it and now it's down to 1 to 1/2 weeks, but I think I've been listening at higher volumes more recently and considering how quickly laptop batteries lose their charge, I think it's held up very well.CONS: There are a couple of bad things I've noticed. First of all, the highs are a little too high for my liking and its the kind of thing you really won't notice unless you listen to it all the time, especially at higher volumes. I solved this using the EQ on Spotify. Furthermore, while the bass sounds good by default I know it can do more, so I set the EQ accordingly. The other thing is really quiet songs at higher volumes reveal a really soft background static from the internal amplifier. This flaw is more than likely inherent to non-grounded amplifiers or ones without room for extra circuitry that can minimize it (but it seems pretty minimal already, so don't worry about this). To be honest, I thought the speaker was so perfect I was surprised it had any flaws.PHYSICAL DEVICE: It's waterproof and I've taken it to dusty and dirty places and washed it off just fine. The water can muffle the sound if it gets stuck on the speakers, but I've been able to shake it off half the time.It's pretty small in person, about the size of a 16oz water bottle and fits almost everywhere water bottles do which is very convenient for taking it everywhere. Compared to similar speakers it's smaller and sounds better.BLUETOOTH: It can handles 2 simultaneous phone connections and trade between them seamlessly whenever the other person starts to play something. I've had issues with 3+ people, but they had iPhones and I think that was the problem because I think I've done 3 Androids before without problems (but iPhones still work well up to 2 devices). Furthermore, the auto-connect only works when it's set for both headset and music, but since I don't enable headset I have to manually connect each time (but I think this is just my phone as other peoples usually auto-connect).Overall, I think this speaker is amazing, better than the older and newer ones, and much better than its competitors. I paid about $85 for this and think it was absolutely worth it, but it's cheaper now and I'm happy it's still available since I think it really is the best you can get for this category.(side note: the pictures are from when I got it, but it's looks almost the same but with the 2 or 3 tiny scratches where I slide it every day)