I'm middle of the road on him. I don't think he'll "distract" the likes of Scoot, Shaedon, Ant, Grant, etc, so like @HCP said, worst-case scenario he's an expiring contract next year thrown in to make money match (and save the Blazers about 120M in commitments). Best-case...he plays point big with shooters all over and anchors the defense.
I'd rather have him (with the pick or two that are coming) than Lowry, Herro, or any other guard that we'd have to spin somewhere else anyway. At least there's a shot of upside (unlike Lowry), or a positional fit (unlike Herro).