Let's get one thing out there right away: to me, a bluetooth speaker is all about portability. I see a lot of reviewers comparing this to the Bose Soundlink. I'm sure the Bose sounds great, but I'm not taking the Bose with me to the beach, camping or by a campfire (I'm certain I'll forget to bring this inside from time-to-time, but it's weather-resistant), boating, in the shower, or anywhere, because the Bose would be ruined. If you're buying a speaker only for indoors and/or mostly for use in the same area, I don't see why you'd buy a portable bluetooth speaker.

Since I started with portability and durability, let's talk about that:
This thing is well-built. I've owned many electronics of all kinds, and I know a well-built device when I see and feel it. It's heavy for its size, and with speakers that's always a good thing in my experience. Light speakers never sound good. That said, it's only 1.2 lbs, which is still very portable and could even be clipped to a belt loop on the little clasp with a carbiner clip. There's even a hole for a camera tripod to mount it on, should you need to (outdoors at a party?) It has a great feel to it with a rubberized, durable, matte/flat finish. The mesh is awesome (the yellow part on this speaker--I got the moss/green speaker). It should hold up very well.

I'm not going to submerge it just to tell you if it survived ;-) I can say, though, that I watched a YouTube review where the person ran it under the kitchen faucet and it kept playing fine. So, at a minimum, it's highly splash-proof.

Size:
It's about the size of 1 1/2 soda cans. About the same diameter, and about 1.5 cans tall. I was surprised by how compact it actually is. Additionally, the round shape makes it easy to carry around.

Set-up:
Piece of cake. A few seconds and you're up and running. There's also an (optional) app you can download for Android (Apple too) which gives additional options, and you can pair it with another speaker. I think the best part of the app is that it tells you exact battery percentage (you can also make the speaker itself tell you that!)

Range: I have a 2,000 sq. ft. house, and I can walk around anywhere, even down to the basement, and the signal stays solid. It has at least a 30 ft. + range (probably more.)

Sound: (tested with rock music, Three Days Grace, Breaking Benjamin, 30 Seconds, Shinedown, etc.)
I'm absolutely stunned by the quality of the sound that comes out of this Boom. I put it at full volume to test it for this review, and I had to turn it down shortly thereafter. Unless you're outside partying, you won't need full volume. Additionally, at full volume, there was absolutely no distortion at all.

Bass: Ok, so everyone apparently wants to talk about bass. I know Bose is known for its bass, and I am always impressed with what they can pump out, but I'm telling you that this UE Boom handles bass very well. I think it sounds excellent. Are you going to feel the bass like you do in a car with an amp? Not really, but I'm nevertheless really surprised by the bass quality of this little speaker.

Vocals: Impressive!! Crisp and clean. The vocals sounded better than on my Onkyo home stereo in terms of quality, not volume, obviously.

Mids/Highs: I think the sound quality is excellent.

All-around, I can't see anyone being disappointed with the sound of this device. I'm amazed at what small speakers are now capable of. The 360 degree sound is excellent, too. It doesn't really matter where you place the speaker or which way it's facing; it sounds the same.