Offensively: Very good skater, although he can tend to carry the puck too much and make some egregious turnovers. Other times he will carve through the neutral zone and really put on the burners. It depends on the night. Has a whale of a shot, and while he had trouble putting the puck on net, towards the middle of the season he went to a 3/4 slap shot and did a much better job in that regard. I'd assume he does the same next season. Power play production is excellent and led the team by a wide margin according to BTN (ignore Semenov there, he had very little PP time). As mentioned before, a good skater, and able to carry the puck below the circles. You're going to be getting a very mobile and active defenseman in the offensive zone as long as Vigneault gives him that opportunity.
Defensively: Definitely not a strong suit here. Tends to make bad reads with the puck at the blueline, and lacks physical acumen. He's definitely what I would describe as "soft", but more than worth his price as long as he is played with a physical stay at home defenseman- probably not a problem considering Vancouver has a lot of depth in that type of player. He was paired with Douglas Murray last season, so maybe Mitchell or Bieksa? Depends on Gillis' impending trade of course, but those are the two that stand out at first glance.
Role: First team power play, very limited PK time, second pairing defenseman. Some nights he's going to look great, the next night he might be better off in the press box (hence the nickname "Error-hoff"). His contract and skill set are definitely worth it though, especially since Vancouver needed some offense from the backend. Very good pickup, and worth 3x what you gave up to get him.
Offensively: Meh. Not too much to say here. You're going to want to pair him with someone who can put the puck in the net on the backend if you're expecting any output from that pairing. Decent to below average speed, definitely a depth guy. Makes smart and conservative passes but isn't going to push the puck up the ice like Ehrhoff will be able to.
Defensively: Meh. First twenty games of the season he looked good, but as the year wore on he tended to slide south. He'll be in a stay at home role next season, but is prone to making a bad pinch every once in awhile. When that happens his skating ability will be exposed.
Role: No power play time, depth PK, bottom pairing defenseman. Not trying to bag on Luko because he's got a great personality (and an excellent singing voice), but my guess is that he was thrown into the deal at the last minute as a favor for San Jose. Good team guy though, and his contract won't be an issue of vast overpayment or anything of that sort.
Obviously Gillis took Wilson to the cleaners here, and I'm sure you're very happy with the deal. Some FTF readers may be by later to chime in as well, so play nice. Especially you, Temujin- we may forgive, but we never forget ;)
Cheers, and good luck next season.