Engadget- "We've been using the peripheral a lot for Monster Hunter 3G since we're sticklers for full camera control with that game. The Slide Pad is even more essential for Resident Evil: Revelations because it improves that game's controls a lot. "But enough about you guys, what about moi?" you ask. Essentially, the decision on whether or not to get the Slide Pad or its Western twin, the Circle Pad Pro, boils down to personal preference.
If you plan on primarily playing games like Super Mario 3D Land or Mario Kart 7, then your gaming life will be just peachy even without the peripheral. But if you're planning to invest a ton of time on compatible games like Resident Evil: Revelations, Metal Gear Solid: Snake Eater 3D, Kid Icarus: Uprising or Kingdom Hearts 3D, then the peripheral is worth a look if you can live with its drawbacks. We still recommend playing those games first, though, just to make sure you even need it."