Scion's are great cars, nothing kiddy about them, they were marketed towards a younger generation to help Toyota out and they succeeded, but given how affordable they are, adults actually started to buy the cars.
They are rock solid and worth it. I myself had an 08 Scion TC for 1 1/2 years and enjoyed it, came with the Infamous Camry 4cylinder engine, the newer XB's come with it to. The XD comes with a solid engine and trans as well, go into it with confidence if its at the right price.