Things to like:
Additions on D
The Leafs got the 3rd best UFA defenceman on the market, an ideal partner for Morgan Rielly, while taking advantage of the depressed economic situation in signing him to a deal that has very little long term risk. They also added a veteran who plays with tenacity & physicality (something that they otherwise lack) -- who should complement the 4-5 guys ahead of him and few behind him very well. Overall, a defensive group consisting of Rielly, Brodie, Muzzin, Holl, Bogosian, Dermott, Liljegren, Sandin and Lehtonen may not be the league's best, but is really solid 1-6, with a ton of depth & upside.
Cap Savings Up Front
The Leafs had to drop money somewhere, and subtracting from the 3rd line wings seems like a really good place to do it. Between the 2 of them (albeit mostly Kapanen), they got a fairly substantial haul of futures (Amirov, Hallander, Anderson), and have replaced them with Vesey & Simmonds. Vesey may put up the same numbers as either of these guys, and Simmonds will bring a lot of the battle that this group has lacked in recent years.
Overall Cap Management
The Leafs could have "gone big" and signed Alex Pietrangelo instead of TJ Brodie. It would have cost them Alex Kerfoot, Wayne Simmonds, and Pierre Engvall (on top of Kap & AJ). While that may have worked this year, it would have put them in a position next year where they must trade a Marner or Nylander in order to fill out the roster.
The way they've position this team from a cap standpoint, Wayne Simmonds & Zach Bogosian's expiring contracts give way to a raise for Zach Hyman. You can realistically start working on an extension for Rielly next summer.
Things to not like (or missed/potentially missed opportunities):
The "Big 4" up front - Dubas set a new market in how he paid RFAs Marner & Matthews, with huge deals, but not getting 8 years out of them. Expecting a rising cap, he signed the top UFA forward 2 years ago to a huge 7 year deal, one that's only really been eclipsed by Panarin last year. The result is having 3 of the top 7 paid players in the league.
IMO, the Leafs "core" has been affected by COVID-19 more than other team, simply because they were tied up for so much money. The cap is projected to be flat (or close to it) for the next 2-4 years. While this year may not have been the year to try and "cash out" on one of these guys, it did seem to be the year where you can really get guys at substantially discounted prices. I look at a guy like Tyler Toffoli as an example, who the Leafs couldn't even consider talking to without the mindset of moving one of those 4 pieces up front.
3rd Line Centre - There seemed to be a decent amount of checking / 3rd line centres out there. It strikes me that this would be an opportunity to get a guy that fits better in this role than Kerfoot at a deeply discounted price, while getting 2-3 years worth of security. So far we haven't seen that happen.
Clogging up the development of defencemen: The Leafs have 4 high upside defencemen that all need to play (Dermott, Liljegren, Sandin, Lehtonen). They've got 2 spots (one of which is the #7 spot) to put these guys. The only one who can really benefit from AHL experience is probably Lehtonen, but he's also the oldest, and will be in mid-season form. I believe that the Leafs need to find a way to "cash out" on the value that 1-2 of these guys posses.
Not Sure What To Think
Goaltending - Frederik Andersen is better than any goalie that changed hands this season, except maybe Jakob Markstrom who you'd be splitting hairs over, and he was of course more expensive... so it's tough to be upset over not making a change.
However, I don't believe Andersen is the long term solution in Toronto (especially considering that he's going to look at Markstrom's contract and say me too), and it seems like a missed opportunity to have him walk as a UFA rather than be used for value and the crazy market this year to find a guy that could be a long term solution.