The PS Vita Compared to a PSP, a DS Lite, a Micro, a Game Gear....

And more. If this doesn't give you an idea of how big the PS Vita is, perhaps comparing it to Ultraman would help?

ゲームギアからPSVitaまで新旧さまざまな携帯ハードの大きさを比較してみた [はちま機構]