Been thinking more about AC Syndicate from a game design perspective of what works/doesn't (yeah, this is what I think about in the shower each morning), because it's an interesting set of ideas that feels like it's trying to throw all the non-game stuff from AC out and focus on AC as its core gameplay mechanics.
Things that Syndicate does right:
+It has that distraction design (not sure if there's an official game design term for it), where everytime you go from point A -> point B on a mission you'll likely run across another mission or some event on the way and then you can start that mission as well and do the mission within the mission first then keep heading to where you are going. It's the same concept of rpgs like Pillars of Eternity where when you're on the way to the next quest objective you'll run across other quests and events. It keeps a good feedback loop of accomplishing things while being a bite into the next quest/mission by the time you're finished with the current one. This design counters the cold stop/start at the end of missions/quests/levels that can be "stopping points" for a player. Places where they would save and turn the game off for the session. But by continually putting the next gameplay hook in there's no stopping point and it keeps the pacing.
+Syndicate also doesn't overload with content. Unity had the problem of like 100 hours of sidequests so everywhere you go it's just sidequest, sidequest, sidequests and the pacing was a bog. In Syndicate, the actual missions are broken down into just 1 for each ward and then after you unlock all the wards, a boss mission for each borough. Additionally there's a few other character sidequests and the main story quests, but it's a good amount of content without being overwhelming, and the main missions constantly take you through wards in boroughs so you'll end up sidequesting to do the missions along the way.
+Missions are short and fast and mostly free-form. Most of the side missions are like 5 minute scenarios of "here is a base, go kill people anyway you want". There isn't a ton to them, but they're fun, quick diversions, which is exactly what they should be.
+Everything is made fast and to the point instead of going for immersion. Whereas past AC games would have lots and lots of running around from point A to B, or in Black Flag's case minutes of immersive sailing where you just sit and hold forward, which worked with the gorgeous sea & sky + your crew singing sea shanties, Syndicate doesn't care about immersion and is for the no patience gamer. You can fast travel a ton, drive a car pretty quick around down, grappling hook instantly up buildings or across. The pace just moves, moves and moves. Combined with the above described 5 minute side mission stops along the way that are numerous but not overwhelming in number, and the first point described gameplay loop, it keeps the game going and tough to put down. Add in that every side mission you do gives skill points, and skill points increase level, and level increases equipable gear, and all that makes your character stronger, it's a very solid loop.
Gameplay things Syndicate still struggles with, or does wrong:
-Controls are still bad and kill you way too much. I think AC could really benefit from a rewind button (maybe with a cooldown to prevent abuse), so that when you're 10 minutes into a mission having stealthed everything perfectly and then your guy jumps to the wrong thing and gets seen and blows the whole thing, a rewind save button would be a lifesaver. The other option would be to spend the extra time polishing the controls, camera and ai so mistakes don't happen, but given we're like 10 AC games in and the controls still have problems (or glitches like when I feel off a building because my guy started climbing the air), a rewind button would be a quick and easy fix that would improve the stealth a whole lot.
-Still too much repetition. You'd think with all the money and staff on these games they could come up with more than like 3-4 activities to do over and over again in slightly different enemy setups.
-The main story missions are often way too scripted for their own good and the engine often struggles with them with the AI doing weird ass glitches and one mistake blowing the whole thing stealth-wise. I kinda think the main missions are the worst part and maybe it'd be better if they were just like "here is a base, go kill that guy" like the side missions but make the base more complex for the main missions.
-Combat's a wash, it's a bit better but still just Arkham light
I think that's most of the stuff I was thinking about earlier. I definitely appreciate the faster, no-nonsense pace. If you're going to make a great epic journey, fine go for the slower immersive style, but if it's just a silly small AC story, than throw it all out the window and just make it an arcade style base attack game, which is what Syndicate gets closest to.