Best and worst two-in-one phone designs (pictures)

The smartest phones serve as nerve centers for computing, communication, and entertainment -- aspirations that yesterday's feature phones and today's superphones both share. At times, manufacturers get creative (sometimes very creative,) attaching extra hardware that turns phones into music, gaming, and photographic workhorses. For better or for worse, these hybrids stand out from the crowd.

Remember the reign of music phones that coupled feature phone capabilities with dedicated hardware controls? Sony Ericsson's W760i Walkman slider was one of the smoothest operators.

AT&T and HTC paired up for the wacky Surround, one of the company's first major experiments with rich audio. Slide out the surround speakers, press the button at the top to activate surround sound, and let 'er rip. Unfortunately, the phone was heavy, the speakers mostly neglected, and overall sound quality a little mediocre.

Small enough to wedge into your pocket, the Sony Xperia Play nevertheless had tiny analog controls for Android gameplay that went beyond tapping and tilting the screen. An ambitious product on paper, the Play's gaming response time lagged and screen quality just wasn't crisp enough.

Outfitted with a huge optical zoom and flexible, easy-to-use controls, the Samsung Galaxy S4 Zoom is more compact point-and-shoot than smartphone. In fact, its cellular radio is almost superfluous. In that light, the awkward-for-a-phone, not-quite-good-enough-for-a-camera Zoom is so niche, it's hard to peg who would really want to buy it.

Nokia took a more focused approached to advanced camera phone mechanics. Its Nokia Lumia 1020 packs in a larger sensor size and fancy 41-megapixel image capture, while remaining just slim enough to carry around. The handset isn't perfect, though, but any flaws in its physical design (like the slightly bulging camera assembly) are minor enough and serve the central function of taking better photos.

The third in Asus' PadFone line, this latest effort -- which we call the Asus PadFone (September 2013) -- pairs a high-powered 5-inch superphone with a separate tablet dock. The phone's processor powers the "tablet" screen and populates its content, too, making this combo a true two-in-one that's also truly compelling.

Rescuing the stylus from fuddy-duddy obscurity, Samsung's Note line reinvents productivity and multitasking with a slim wand that helps out with a few tricks of its own. Samsung's Galaxy Note 3 takes multitasking even further with some new moves.