Lop the disc drive off Sony's PlayStation Portable and add a Mylo-inspired slide-screen gamepad, and you get the PSP's smaller, lighter, more dearly priced cousin--the trendier PSP Go. Sony has hiked the platform's price tag from $170 to $250, five-sixths the cost of a new PlayStation 3 or Xbox 360 Elite, a reprogrammable gaming robot, or dinner at Heston Blumenthal's exalted restaurant, The Fat Duck. In exchange you get nips and tucks in the weight and size, a modestly retooled grip interface, Bluetooth support, and 16GB of internal flash memory.

Nintendo has whittled down its DS twice since launch, so competitive turnabout is fair play. Sony's PSP Go is actually the platform's fourth metamorphosis, lowering the handheld's weight to 5.6 ounces--16 percent lighter than the PSP Slim and 43 percent lighter than the original PSP-1000. It's also 35 percent smaller than the PSP Slim, packing everything the older model had except the UMD drive into a third less space, and that's including the 480-by-272-pixel widescreen LCD. The flip side: The LCD's pixels now occupy less physical space, since Sony shrank the diagonal span from 4.3 inches to 3.8 inches. The ramifications vary by game, but if you've ever struggled to read on-screen text in a PSP game or legacy PlayStation 1 title, count on the Go not to do your eyes any favors.

As an objet d'art, the Go--an elegant black rectangle cradled between glossy, beveled half circles--runs rings around its predecessors. It comes in two colors, "piano black" or "pearl white." The high-gloss black model is a fingerprint magnet, expectedly, but the slide-out gamepad mitigates that by employing a matte finish that's more resistant to smearing. You'll still want to keep a cleaning cloth handy for the screen, of course.

Everything except the PlayStation menu button, the stereo speakers, and the network indicator lights has migrated to the slide-out gamepad and between the shoulder buttons along the system's top side. Pop the gamepad out, and the d-pad and buttons now rest below--as opposed to along either side of--the LCD (ditto the select/start buttons).

The boldest change, whether intentional or born of spatial necessity, is the relocation of the thumb-nub (the 360-degree joystick that's almost flush with the surface): It now rests immediately to the right of the d-pad. On older models it was positioned below the d-pad, to the left of the screen--an awkward position that led to cramping with extended play, since your thumb jutted out with no place to rest. The PSP Go's nub sits where your thumb naturally goes, eliminating the strain issue. The nub's smaller size also allows medium-size fingers to interact with the device more precisely, though gamers with thicker fingers may find it difficult to maneuver.

The Go's smaller, silver-tone shoulder buttons correct a shortcoming of older models, as they're much quieter when rapidly pressed. The audio controls and brightness settings, meanwhile, have relocated to the side space previously occupied by the mini-USB connector, where they're easy to get at--until you slide the device open. Thereafter you have to flip the unit 90 degrees to see them. It's too bad Sony didn't opt to slip them into the empty space below the stereo speakers, or even above the nub and start/select buttons on the gamepad itself.

Replacing Sony's proprietary Memory Stick Pro Duo slot is an M2 Micro memory card slot (basically a smaller card that currently tops out at 16GB storage capacity). It's designed to complement the 16GB of internal flash memory that comes with the system.

You'll need every last byte of that flash memory, too, since the Go eschews the platform's long-standing UMD tray--the square, hinged panel on earlier PSPs that let you load tiny plastic-sheathed discs bearing games or movies. That's the Go's rebel yell: gaming without discs or cartridges. And while its predecessors offered the option via the Memory Stick Pro Duo, the Go is the first dedicated handheld game system to make it mandatory.

Out of the box and the store, therefore, you are effectively game-less (save for a preloaded demo of Sony's real-time drum-tapper, Patapon 2) until you link up with Sony's PlayStation Network by means of the Go's dated 802.11b wireless interface. Why Sony couldn't be bothered to include an 802.11g chip is anyone's guess. Sure, conventional broadband will bottleneck before hitching on the 802.11b spec's 5-megabits-per-second average throughput, but if you need the speed on your LAN, the Go won't let your access point give up the mixed-mode ghost.

Included in the box is Sony's new MediaGo software, an iTunes-like application that facilitates library management of your movies, music, and games. Moving games between PSPs is a simple matter of dragging them to and from MediaGo's library.

Unfortunately, you get no option to rip UMD games or movies. Since Sony has backed away from a goodwill program offering digital vouchers to gamers who already own the UMD version of a title, the only way to get the games onto the Go is to buy (and download) them again. New PSP games average $30 to $40, so someone with six recent UMD games faces the prospect of forking over $180 to $240 to get around this egregious oversight. The tape-to-CD or DVD-to-Blu-ray defense falls down here, since those transitions were about media improvements--Sony's digital downloads, in contrast, are byte-for-byte identical to their UMD counterparts. If you're heavily invested in UMD gaming or movie viewing, you should avoid the Go entirely until Sony offers a reasonable upgrade path.

The Go's battery life compares favorably with that of the original PSP, lasting for about 5 hours of active gaming, and more if you keep Wi-Fi disabled. Wi-Fi remains a drain on power, of course--if you're planning to download a largish game, you'll want to leave the Go plugged into a power source. I left my review unit on overnight to pull down God of War: Chains of Olympus, and it ran out of juice before finishing, corrupting the data and forcing me to download the entire game again. A resume function (with an error-detection option) on the PlayStation Store would certainly help. A background-download option would be great, too; unlike the PS3, the PSP locks you out until it's finished downloading.

Then there's the question of what the Go is missing. Where's the GPS? The touchscreen? The microphone? The built-in camera? The gyrometer that lets you tilt the system and play iPhone-style motion-sensing games without the gamepad? Missing in action, every one. (Of course, you can find all of those features on a subsidized cell phone. Nobody is offering a subsidized PSP Go. Yet.) Instead, you're left with a PSP in a smaller, prettier case. And for that, Sony is asking $250--or $80 more than the cost of its last model. No surprise, then, that gamers and retailers are fit to be tied over the price tag.

Should you get one? Sony has made it hard for even affluent enthusiasts, since the company is asking for $250 up front as well as the cost of repurchasing games already owned in UMD format. At the other end of the spectrum, casual gamers who have never owned a PSP will probably balk at the price tag and opt instead for Nintendo's cheaper, more family-oriented DSi.

Taken as is, the PSP Go is a pretty piece of handheld gaming kit, but--as with the PS3 three years ago--Sony is positioning it incorrectly for the demographic groups it needs to win over most.