Comparing to other 6'5+ players is silly. I see Malkin/Spezza type of play. Obviously he has a low chance of reaching that level (especially Malkin, Spezza is more reachable if we exclude the Pizza days and they're both Spitfires lol).
Your description of Brown is very off, other than saying he's "big"... He's definitely not slow, both objectively and subjectively (relative to his height). He's faster than guys like Getzlaf and Spezza were when drafted, that's for sure. "Decent hands" is selling him short for probably his best asset other than his vision. He's better than a "good playmaker", and as for your doubts on his vision and smarts translating to the NHL, I guess time will tell, but I highly doubt your doubts...
The bold is odd to me because he's never played in the NHL. If you want to make that judgment you should at least wait until he plays a couple of games here. I realize you probably mean against NHL-caliber "prospects", but that's just a weird statement to make.