At MWC 2012, Nvidia demoed quite a few games, but Sonic The Hedgehog 4 Episode II was easily the one that impressed us the most.
This week, Sega finally released the game. Yesterday, it became available on the PlayStation Network. Today, though, it's available for Xbox and Tegra 3 owners. (Price is $6.99 on Google Play and TegraZone.) Tomorrow, it will be presumably on Apple's App Store for iOS devices (according to Sonic Wikia page). Support for all Android devices will come in another month, which is why Nvidia is keen on highlighting the benefits of Tegra 3 now.
It's difficult for us to make the comparison ourselves. Right now, the app is locked down to Tegra 3 devices. We were able to install the APK on other devices (including Tegra 2), but the downloadable content needed to launch the game doesn't seem to be available unless you own a Tegra 3 device. We're assuming that's done to give Tegra 3 the spotlight.
Nvidia did provide some side by side screenshots that are supposed to illustrate the improved graphics of its third generation SoC. According to the company, "Sonic on Tegra 3 has dramatically higher quality textures, better lighting and glow effects, and objects on screen that are absent from other mobile versions."
From a gameplay perspective, the touch controls felt a little foreign to us. Perhaps, that's because we're so use to playing anything Sonic-related on a console or PC. That said, the spin and jump action share the same button, which is kind of annoying. Fortunately, this game works fine in what we call "console mode." You just have to get external controlled (i.e. Xbox360 Wireless Controller & PC receiver dongle) and hook up your Tegra 3 device to a TV. It's incredibly close to the console experience.
This game does fall short in some ways though. The multiplayer co-op mode allows you and a friend to partner up as Sonic and Tails. The hiccup is that you need a two Tegra 3 devices to make multiplayer work. You can't just run two wireless game controllers off a single Transformer Prime hooked up to a HDTV. That's our only major complaint. Otherwise, this another game that we'd recommend adding to your buy list.