Not as groggy, more wargamey. Overall I think I enjoyed SH3 more than Cold Waters, just cause it felt like you were more in control.
Gameplay of Cold Waters basically goes you're given a mission target and placed on a map and various contacts show up as they pass through sonar pickets or show up on aerial recon. You use your briefing to feel out which contact is the target (usually not that hard) and then move to it by dragging your mouse across the map, trying not to get caught by anybody else.
Then once in the battle you try to kill the enemy. Interface is more abstracted than SH3. You don't use the waterfall to find targets, you don't take over the different posts to get their info, the game assumes your crew is doing their jobs and sending their findings to you in a readable format. All you really have to do is correctly interpret that information and use good tactics. Game's pretty hard. Soviets are aggressive with active sonar and have really nasty AWS hardware so if you give yourself away they're gonna be on you hard.
SH3 has a steeper learning curve with the deeper simulation, not to mention the difficulty of playing as the losers, where late war just getting back to port alive is cause for celebration. But I think that makes it more rewarding, and generally feels better for me as a sim guy. It's hard to tell exactly what's gonna happen when you enter a battle in Cold Waters. It often puts you in awkward positions and if you don't know about stealth movement you're probably going to pop up on passive sonar as soon as the match starts.
Meanwhile in SH3 I have complete control. I can get my cute little map and my cute little compass and protractor and do some cute little trigonometry to determine exactly where and when I want to be and slide silently into a perfect broadside firing solution.
Also wire breaks will make you rage. Nothing like winning a hard fought battle only to hear a torpedo you launched twenty minutes ago start pinging you.
If you enjoyed the difficulty and fidelity of SH3 Dangerous Waters might be more your speed. It's a brain melter but very rewarding if you can handle it.