LG's Optimus 4X HD is here with a 1.5GHz quad-core Tegra 3 chip inside and a 4.7-inch 1280 x 720 IPS display on the outside. This flagship device, only the second (official) Tegra 3 phone we've seen after Fujitsu teased one at CES, runs Android 4.0 Ice Cream Sandwich with an LG skin on top.

We played with the 4X for a few minutes here in LG's booth ahead of the official opening of Mobile World Congress tomorrow, and it definitely feels like a departure from every other Optimus model we've used in the past — the texturing on the rear and the clean squared-off styling is definitely indicative of a high-end device (which the 4X certainly is). In our brief testing, it's fast, but you really can't be sure about how well the Tegra 3 is going to hold up under pressure until you load the phone down with apps and full desktop versions of websites.

Is it ready to take Samsung's next-gen Galaxy S model head-to-head? We've got a couple complaints that knock it down a notch: for one, there's some odd design in the chrome styling along all four edges, which looks more suited for a low-end device that's trying to look aspirational (and failing). Don't get us wrong — the appearance of the 4X overall is quite nice — but this particular detail is oddly out of place. Perhaps more importantly, the 4X has just three capacitive buttons along the bottom (as most native Android 4.0 devices are expected to have), but strangely, the third button is operating the menu, not the multitasking screen. This seems like it's probably just a nuance of the pre-release firmware, though, because a hard menu key simply doesn't make sense here — and the iconography leads us to believe that multitasking is the intended function anyway.