First, I will note I never played a previous SOCOM game as I never went online with the PS2 and Confrontation was definitely a bad game when it launched so I never picked it up.
I played the SOCOM beta or demo, and I was really disappointed by it. I went in expecting a hardcore shooter like Metal Gear Online but based more in realism than MGO. SOCOM4, in my opinion, basically plays like a 3rd-person COD that's has a lot more camping spots. There's health regen, grenades are one button throws (in my book, you should have to cycle from your gun to your nade like MGO and MAG), and there's moving spawns (which I also hate). There's classic SOCOM mode with no respawns and a standard health meter but respawns aren't a bad thing for most game modes. Why can't I play with a health bar and play a respawn game? The game is also all matchmaking and I prefer games with a lobby/room system. The cover system that's in the game is pretty clunky and I hate the fact that you can't switch shoulders when shooting.