You can benefit from doing some googling on the components you are looking at. Typically brands like Alpine, Pioneer, Sony, Kenwood, Kicker, JBL, and Polk audio are the best money can buy.
If it's audio you are interested in, I would just make the investment in a high quality amp and then buy the accessories to wire it up to play your ipod directly through it. But if you're hell bent on the simplicity of plug and play, then the amp you linked to will probably be alright for a while.
I drive a Cherokar.