With so many bluetooth speakers out there, it's hard to go wrong. I have used at least a half dozen different brands / models and they are all awesome. The Skullcandy Air Raid is a solid option if you are looking for good quality audio that BUMPS. It's basically two Shrapnels in one (but easier to use) if you are familiar with Skullcandy's smaller bluetooth speaker.
Design: It is a fairly basic piece of equipment. It's a rectangle about 6" x 3" x 2" (approximately, that is width, height, thickness). On the left side is the on/off switch and a bar for attaching a lanyard to. The front features the two speakers with the volume and bluetooth connect button in the center. The right side has a metal ring / oval that swings out for hanging. The top, bottom, and rear are all covered with a thick rubber protector. The power and input are in the rear.
Weight: It is definitely the heaviest out of the three bluetooth speakers I have (OT turtle shell, Sol Republic X Motorola Deck), but it is definitely the burliest. This thing can take a pretty big fall and be fine. A little bit of weight isn't a bad thing though, it's less likely to fall if you bring it on a boat or if you are using it on the go in some sort of vehicle.
Battery Life: It is up there with the Turtle Shell in battery life, which is somewhere around the 8 hour mark. I have used both for much longer than the companies state they are good for. No sign of battery life reducing after 3 months.
Features: Real basic. Volume and bluetooth pairing. No skip function (at least that I can find or figure out, sometimes the volume buttons work as skip / fast forward / rewind, but it does not appear that way on the Air Raid. No sort of bass / treble function.
Sound Quality: Better than both the Sol Republic Deck and my Turtle Shell (original one btw, I know they have improved it). It is definitely the loudest of the bunch, and the quality does not dissipate as the volume increases.
Fit / Wearability: Pretty bad. This is more for sitting on your table / desk / ground / dashboard / whatever. Will not fit comfortably in a pocket, cannot mount to a bike or anything like the Turtle Shell, and even though it has the ring to hang it, it's better off on a flat surface. If you want a bluetooth speaker to throw in your pocket on the hill or stuff in a backpack while doing whatever sport, this is not what you are looking for.
Overall: Love it. Like I said, it has its downfalls but I have other speakers that fill the functions the Air Raid fails at. Definitely worth a look.