IMO Gillis was an excellent GM when he first came in(outside the organization) with an open mind and some fresh ideas. He knew that upgrades needed to be made and identified the team's weaknesses and addressed them pretty effectively. He even got AV to change his coaching style to more of a puck-possession, skilled, offensive style of play.
However, IMO over time he's started to give AV too much input on player personnel moves/decisions and also allowed AV to go back to more of a defensive, dump and change style system. The Bruins SCF loss also seems to have changed his management style. He hasn't replaced the skill(by skill I mean puck moving/PP/pure offensive ability) players that he's let go over the years in:
Ehrhoff(Garrison is nice, but not a puck mover that can help the transition game and feed the forwards nice passes 5v5 and on the PP, more of a Salo replacement/upgrade that's much more durable/physical and more accurate with his slapper, IMO his defensive "problems" were overstated, I'm still amazed that Ballard wasn't just waived and then Hoff could have been paid the 5 million he probably wanted over 5 or 6 years).
Hodgson(Who knows what really happened here, but either way this organization took a hit offensively and in skill with that trade). Trading for Roy essentially filled that role now and I loved that trade for that exact reason, but Roy is very likely a playoff rental player.
Demitra/Sundin(RIP Pavol, both solid veterans that just brought that confidence to the team that good veteran players do).
Samuelsson(Clearly was slowing down and breaking down, but Booth clearly didn't replace his skill and PP ability, players that play well off of the rush like Booth usually thrive with pass-first centers and skilled, puck-moving d-men and I'm guessing he would have better numbers had Ehrhoff and Hodgson or similar replacement players still had been on the Canucks and if Booth could actually stay healthy).
You can even include a guy like Wellwood, for as much as he's always made fun of, he brought some skill and was useful on the PP. I'd take him over Ebbett.
Another head scratching move was letting Torres walk because the Gillis didn't want to give him a multi-year deal, and then Gillis ends up trying to re-acquire him only to be outbid by the team that we're now playing in the playoffs.
Also, Gillis came into this season with 4 left-handed d-men making top 4 money, after letting two proven top 4 righties in Salo and Hoff walk. And the only proven top 4 righty on the roster was Bieksa, after that it was Tanev and basically nobody until Corrado was called up and thankfully has played very well with all things considered. It's amazing that the scout who recommended Cam Barker even has a job, and that all of the depth d-men that Gillis signed were all lefties.
Also, another thing that scares me is that apparently Kyle Clifford was rumoured to be one of those 6 players that Gillis would have dealt Hodgson for! And I'm not a Kassian hater(It's quite clear that he has great upside if it all comes together for him), but Kyle Clifford projects to be a third liner, maybe a low end 2nd liner at best so that's a scary thought.