There is only one "team" to play
You cannot seem to drive cars/or blow them up
Infact in Syndicate Wars lots of stuff was destructable, in SR basically nothing is
No flying cars
No huge tanks that shoot missiles at you or those huge spider tank things (infact there are spider tanks in Satellite Reign but they are patetic)
Lack of explosive stuff in general
You cannot pick up/drop weapons (this is retarded)
No trains
The level design is also less creative, basically evert part of the game is the same in SR. The gameplay throughout is just very samey. Basically you go to various sectors of this one big city which all look the same, break into certain locations to gain stuff and thats pretty much all you do. There are very few missions that take place in the public areas, and the few that are will be to pick up a package or kill someone, they are straightfoward. No ambushing you, or surprising you like the old games did.
They have added a stealth system in, so when you enter locations you can disable security cameras etc, and sneak around, however it is clunky, to the point where jsut walking in and shooting is better. They have set it up so you can go through the vents or side passages or whatever, but there is little point when its easier jsut to walk in the front door shooting, and when did a Syndicate game become about stealth anyway??? The combat is slow compared to the old games. There are no also enemy agents, only police and security, which do differ in strength, however even the elite bad guys are no real threat and the only real threat is when you become outnumbered.
The tech tree is also messed up. The way the game works there doesnt appear to be any major order in which you gain tech, or for my playthrough, I ended up getting the second best weapon about a quater of the way through the game which means I only ever ended up using about 4 weapons in total. As you can easily jump ahead, most of the weapons/gear/augmentations effectively become redundant even before you get them, which is a shame.