I've seen some mixed opinions about the return of Andre Miller here, so I just wanted to offer you all my perspective as a Blazers fan.
First of all, I don't know if you guys are getting back the same Andre Miller that played for Denver a while ago. I've seen comments about how he bogs down the offense and dribbles down the clock too much. Maybe he's gotten better since then, but in his time with Portland, he was our offense. He was the only thing that made our offense tick. Whenever he left the game, our offense fell apart. On the court, he was one hell of a point guard, dishing and alley-ooping like no other. He's one of the sole reasons Lamarcus Aldridge was able to have a break-out season this year, after 4 years of mediocrity (by his standard). Basically, Andre Miller unleashed him.
It's also a pleasure to watch him work the post. Russell Westbrook has since learned, but one of my favorite things in basketball was watching Dre embarrass Westbrook with his pump-fake. I don't know how high his BBIQ was when he left Denver, but one thing's for sure: He's returning to your team a savvy veteran in the truest sense of the word. Also, he's become a flat-out warrior, pretty much carrying Portland to the playoffs these past two seasons.
Of course, some things haven't changed. He still has a weak jumpshot. I know some will say "weak" is an understatement, but even then he's improved somewhat. He's still clutch and can make big shots when it counts, ie. he was almost 50% from 3-point range in the playoffs. But don't expect a new found silky smooth shot form. He's also still a mediocre defender and has trouble containing quick guards.
Playing style aside though, you have to understand that he won the hearts of the majority of the Portland fanbase. Just a quick skim of Blazersedge.com right now and you'll find many people who are absolutely heartbroken Dre was traded. A lot of executives in the Blazers organization absolutely love this guy, and Lamarcus Aldridge called him something to the effect of "the best teammate I've ever had" this year.
I think he has the potential to legitimately challenge Ty Lawson for that starting spot (it'll be interesting to see how Karl works it out), because he pretty much just played the best season of his career this year. He's old, yes, but he'll be able to keep going for a long time the way he plays. In my opinion, now is an exciting time to be a Nuggets fan. Your team is deeper than ever, and you guys have every reason to enjoy the return of Andre Miller.