Got ranked unlocked. The only mode I've played so far is Rainmaker, which definitely feels different. The weapon itself has been modified and now shoots explosive projectiles instead of a tornado, and it now has a timer that kills its wielder after a certain amount of time. The net result seems to be that the opening few moments aren't quite as crucial, and a team wipe at the very beginning is less likely to lead to an instant win. A single squid with the Rainmaker can no longer lay down huge swaths of ink and swim directly to the goal since the new fire mode requires many discrete shots to create a path. So teamwork is more important (I've seen people split up and have two go after the Rainmaker and two create a path if they manage to get ahold of it and it's pretty effective) and I guess turtling is less viable, although I never really saw much of that anyway.
I haven't played tower control yet, but I hear the tower now has to stop at checkpoints, which puts the team holding it on the defensive while the other team gets to take potshots at a stationary target. Once again this seems like it eases off on punishing early mistakes and makes it so an early team wipe no longer means that you can just get most of the way to the goal before your opponent regroups. We'll see how it works in practice, but there definitely seems to be a trend toward making ranked matches more uniform in length.
Meanwhile I played with a bunch of weapons in Sheldon's shooting range and realized that a bunch of subweapons that I thought had been removed are in fact still in the game, including the Splash Wall which was arguably the best one in the last game. My beloved Beakons are also still around, but there isn't an Octobrush with them available, maps are smaller which makes them weaker, and you can now only have three in play at once (which I think it down from the first game?). I guess because there are more subweapons some of them are just more dispersed which is why I hadn't seen many of them. Seekers are replaced with a new (and seemingly weaker?) Autobomb and the Disruptor is replaced with the Poison Mist, but everything else is back as far as I can tell.