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LG kicked off Mobile World Congress 2012 with a bang today, announcing the world's first quad-core phone, a pen-based 5-inch handset, a phone that converts 2D games to 3D, and three new style-centered devices. In their own ways, the six new phones reinforce LG's emphasis on speed, style, and quality displays.

LG Optimus 4x HD: First With Quad Core

The first handset powered by Nvidia's quad-core Tegra 3 CPU, the Optimus 4x HD features a brilliant 1280 x 720 IPS displays, which really made colors pop when we watched a video and observed an LG rep playing games on it. At 8.9mm the Optimus 4X seems incredibly slim, particularly when we held it in our hand. However, the company hasn't used thinness as an excuse to skimp on battery life as it has included a 2,150 mAH battery on board, which is not quite as dense as the Motorla Droid RAZR Maxx's 3,300 mAH unit but is much higher capacity than your typical 1800 mAH phone battery.

Running on Android 4.0 Ice Cream Sandwich, the LG Optimus 4X also sports 16MB of internal memory, 1GB of RAM, an 8-MP back-facing camera and a 1.3-MP front facer. There's no word yet on availability, but we believe it offers 4G LTE coverage.

In a brief demo, LG reps showed us how the 1.5-GHz Tegra 3 CPU enables the Opimus 4X to excel at gaming as it played Nvidia's glow-ball demo with full shadows and physics effects while a dual-core phone appeared slow and clunky. We also saw a full HD video playing on screen with the device able to zoom in and out of the video as it continued playing.

LG Optimus Vu: Scribble on a 5-inch Display

If you liked Samsung's Galaxy Note, you'll also be intrigued by LG's Optimus Vu, a 5-inch phone that's designed for note-taking and scribbling of all kinds. At 650 nits, the Vu's 1024 x 768 resolution screen is one of the brightest we've ever seen. Its dual-core 1.5-GHz processor, 1GB of RAM, and 32GB of internal storage should provide plenty of pop while an LTE radio provides the Vu with the fastest 4G speeds. The phone comes with Android 2.3 Gingerbread, but will be upgraded to Android 4. 0 Ice Cream Sandwich.

Though the Vu has a large screen, it's only 8.5mm thick and, though the weight was not disclosed, the device felt very light in our hands. The real star of the show here, though, is the deep pen integration. A button at the top of the phone lets you take a screen shot of anything on the screen and then scribble on top of that picture with your finger or an included stylus.  Once you're done scribbling you can share your image via any included service: email, social media, etc.

We had the chance to go hands-on with the Vu and here impressed with the brightness of the screen and the overall lightness of the device. The pen / screen shot feature seems intriguing, but our scribbles seemed to suffer from a little lag and the pen is not an active stylus so it's really no better than any third-party capacitive pen you can buy for any touch screen device. In fact, there's no place on the phone to hold the stylus and the tip of the pen is a mushy rubber circle not a hard point. Still, we can't wait to try out the device and see what else we can do with the scribble software and other unique apps.

LG Optimus 3D Max Takes 3D to the Next Level

An update to last year's LG Thrill (aka Optimus 3D), the Optimus 3D Max sports a thinner, lighter design and improved software to go with its glasses-free 3D screen. As with the Thrill, LG includes a 3D user interface, some 3D games, and dual 5-MP cameras for shooting 3D photos and video. Currently running Android 2.3 Gingerbread, the 3D Max will be upgraded to Ice Cream Sandwich in the future. The new device measures only 9.6mm thin and weighs just 148 grams, but perhaps its best feature is its software.

In a brief demo, an LG rep showed us how the phone can convert normal 2D games to 3D, even allowing you to set the depth. We watched as he took a game of Angry Birds Seasons, a game not made for 3D, and converted it into a vibrant three-dimensional app using the bundled software. A hardware button on the top of the chassis even allowed him to toggle back and forth from 2D to 3D while playing the game.

The LG rep also showed us a bundled 3D movie editor that, with just a few swipes and taps, allowed him to stitch together different clips he'd shot and even add background music. The whole video took only seconds to render.

Though it has 5-MP cameras just like its predecessor, the Optimus 3D Max has improved 3D camera software which can judge the distance between two objects it is shooting and report back to you. The rep was able to show how many meters apart two of us were standing from each other.

LG's L Series is Filled with L Style

With an emphasis on design rather than additional features, LG's new L Series has aesthetic features like metal accents and textured backs. Ranging in size and functionality from the low-end 3.2-inch L3 to the mid-range 4-inch L5, and the high-end 4.3-inch L7.

In a brief demo, we were particularly impressed with the L7's bright 1280 x 720 screen and its button row, which features a physical home button and two capacitive buttons for back and menu. The device will launch with Ice Cream Sandwich, but it uses this button row instead of a putting virtual buttons on the bottom of the screen like the Galaxy Nexus.

Available in back or white, the Optimus L3, L5, and L7 will launch later this year with Ice Cream Sandwich.