In a list of free agents to beware of.  Their take on his defense is a little ungenerous (although I think some people on this forum also overstate his defensive ability -- he strikes me as at best an average defender who looks good in comparison to his poorly defending teammates).  Overall, though, this strikes me as right.  We should not pay more than the tender offer for this extremely limited player.  Anyways here's their commentary:

Nick Young, SG, Washington Wizards

No statistic tends to be overvalued in free agency more than scoring, so Young's gaudy average of 17.4 points per game last season figures to catch the eye of some team. Young's scoring substantially overstates his value. His efficiency actually wasn't bad; he made 38.7 percent of his 3-point attempts and shot 81.6 percent from the foul line. Add in how rarely Young turned the ball over, and he was an above-average scorer.

The problem is that Young doesn't provide a team anything but points. He's a poor rebounder for a shooting guard, and just three regular players at the position handed out assists less frequently. Add in Young's indifferent effort on defense, and he's the NBA equivalent of a candy bar: all empty calories. Even in his breakout campaign, he rated below replacement level.