Concerning Blacklist, it was pretty good that Ubisoft re-purposed Conviction's building blocks to create level design that facilitated a variety of approaches and play styles, but that doesn't feel ideal for a lot of Splinter Cell or stealth game fans. To me, the levels in Blacklist kinda felt like platformer levels or something -- like slightly more intimate Assassin's Creed maps or something. That method works, but it still produces a very different feel from the firs three Splinter Cell games, particularly Chaos Theory.
CT's levels felt very systemic, even the more linear ones, and in general more interactive. The way you could interact with objects that affected light, sound, the AI, and security systems felt deep and immersive. Blacklist in comparison approaches these things in more gamey "on, off" kind of way.
I don't expect Ubisoft to make that kind of game anymore though unless Clint Hocking is involved (he is back at Ubisoft and we don't know what he's working on). Ubisoft today is all about very gamey systems built around XP and whatnot. It wants open, emergent games, but not in the immersive sim style you got with Chaos Theory, Far Cry 2, or Dishonored.
And yeah I think the soft reboot decision with the story of Blacklist was a mistake. Ubisoft needs to let go of Fisher and at the very least retire him to being the guy in your earpiece (so they can get Ironsides back). Basically every Ubisoft game recently has been create-a-character anyway.