Nintendo DSi XL, "solid." Considering it outsold both the PSP and PSP Go combined, we're inclined to agree.
According to NPD figures (via Gamasutra), the DSi XL sold 141,000 units in March, besting PSP's combined 120,000. Even more impressive is that this figure only accounts for four days of sales; the DSi XL was released on March 28th. The tremendous success of the equally tremendous device confirms that there truly is "room to grow" for the DS market.