I don't know why the Suns had to give up a pick, even a late first-round one, to get this deal done. Perhaps Dragic has very little value in the eyes of most GM's, which would not be surprising. Certainly his career numbers or performance this year wouldn't garner much interest, but Houston was desperate to trade Brooks since he already lost his starting job to Lowry.
I like the fact that the Suns management were fully aware of our biggest weakness recently, namely lack of offensive production while Nash in on the bench, and tried to address that with this trade. I don't know if it will help, but I imagine it can't possibly hurt in that regard.
As was pointed out, Brooks was hurt early this year and when he came back he lost his starting job, so his numbers this year aren't very indicative of what he can do. On the other hand, the Suns will have him coming off the bench as well, so he'll have to be a little more productive and consistent in that role.
As for Dragic, it is not entirely his fault the Suns struggled when he was on the floor, but there is no denying that he has taken a major step back from last season. Overall, I don't mind this trade. But I wish the Suns could have gotten the Milsap deal done.