The Good: For such a small, portable Bluetooth speaker, the Bose SoundLink Wireless Mobile sounds great and plays impressively loud without distorting. It also has a built-in rechargeable battery, an auxiliary input, a rugged design, and the option to swap out protective covers (one of which is included). The Bad: The speaker is pricey and has no speakerphone capabilities. The Bottom Line: If you're willing to pay a premium, the Bose SoundLink Wireless Mobile speaker is the best portable Bluetooth speaker on the market. Editors' note: As of September 2012, Bose has released the Bose SoundLink Bluetooth Mobile Speaker II, which offers improved sound quality and a slightly different cover design. As such, we've adjusted the rating of this older model (which is still available as old stock is sold off).Bose, create a ground-breaking product? Sure, the company's got some really nice headphones and decent sound systems that are just a tad overpriced. But Bose? Since when does Bose make a game-changer?Since it came out with its compact Bluetooth speaker, the SoundLink Wireless Mobile, that's when. No, it's not the iPhone or anything, but it may just be the iPhone of portable Bluetooth speakers. For the uninitiated, Bluetooth speakers let you stream music and other audio from any smartphone and many tablets (including the iPad) wirelessly. There's no need for network configurations--just a simple pairing procedure, and whatever you're playing on your phone or tablet gets wirelessly sent to the speakers, whether it's MP3 music, Spotify, Rdio, a baseball game, or a video soundtrack. Bluetooth speakers have been around for years, so what's so special about the Bose? Well, it starts with how small it is and ends with just how much sound comes out of it--and impressive sound at that. Bose also seems to be taking a few cues from Apple: along with the compact shape and clean, elegant design, the SoundLink Wireless Mobile, starting at $300, is equipped with a magnetic protective combined cover and stand that automatically turns the speaker off when closed. Sound familiar?Oh, and like the , the SoundLink Wireless Mobile's cover comes in two grades: nylon and leather. But you only get the leather cover from the get-go if you step up to the higher-end version of speaker, which costs an extra $50 and has what the company calls an "automotive-grade" chrome trim.Should you buy that fancier silver model or stick with the standard black model with its dark-gray nylon cover for $300? That we can't answer for you, but the truth is you can't go wrong with either model. And, not surprisingly, Bose is selling additional nylon and leather covers in a wider variety of colors for $30 and $50, respectively, in case you want to make a change later.Design and features The first thing you notice about the SoundLink Wireless mobile speaker when you pick it up is that while it may be small, it's got some heft to it, weighing in at 2.78 pounds. It's 5 inches tall, 9.5 inches wide, and a scant 1.9 inches thick.That depth--or lack thereof--is really the most impressive part of the design. But while the SoundLink Wireless Mobile speaker looks sleek, elegant, perhaps even a bit dainty, and would seem more suited to indoor listening, Bose has made a point of touting how durable and rugged the unit is. The company says it has extensively drop-tested the product, and even put it in a chamber and exposed to simulated salt-air fog. So, yes, this is designed to be a portable, outdoorsy product. Further boosting its portability is the built-in rechargeable lithium ion battery, which is rated for 3 to 4 hours of use at high volume between charges. The SoundLink Wireless Mobile has a wireless range of about 30 feet and works with any A2DP Bluetooth-enabled device, which includes nearly all smartphones, as well as the iPad. Around back you'll find a standard 3.5mm audio input for connecting (via an included cable) any other audio devices that don't offer Bluetooth, like an iPod Nano, for instance.We had no trouble pairing an iPhone, an Android smartphone, and an iPad 2 with the speaker. You simply hold down the Bluetooth button on top of the speaker and it goes into pairing mode. After you select "Bose SoundLink Wireless" from the Bluetooth setup menu on your phone or other device, after a few seconds you should be linked up wirelessly to the speaker and be able to stream audio to it.At one point, we did get some dropout from the Android phone--just for a couple of seconds. It was an instructive reminder that Bluetooth, like all wireless tech, just doesn't have the 100 percent reliability of a wired connection.Another note: the SoundLink Wireless Mobile does not offer speakerphone capabilities the way the Jawbone Jambox does, for example. Could it someday offer that feature? Probably not, considering there's no built-in microphone that we're aware of. However, there is a Micro-USB port on the back of the speaker labeled "service," which is for firmware upgrades; Bose says it will offer software upgrades to make sure the speaker is compatible with future phones. We should also mention that the SoundLink Wireless Mobile speaker doesn't come with a remote. That's because you shouldn't need one since you'll be able to control the volume--and everything else--from your smartphone.