I guess I will give some thoughts on this.
If have played Dead Rising the gameplay mechanics are basically the same.
You and your little girl are trapped in a Vegas-type, zombie-infested city. The rescuers come for you in three days. You(Chuck) are framed for starting the outbreak and need to clear your name before the rescuers come.
Your daughter has been bitten by a zombie and needs a special(and expensive) medicine every day between 7am and 8am otherwise she "turns." Which is actually a pretty cool cutscene. And your dumbass didn't have any medicine on you when the city went to hell. Good job daddy.
If you screw up any part of the main quest by not finishing it in time you get three options. Reload, keep playing, or start and new game with your current level. If you keep playing you can do everything else but the main quest and get different endings. You spend most of your time rescuing survivors, doing the main quest, and looking for medicine.
It is difficult to do everything in this game without leveling up which is why your level carries over. Some players just use a playthrough to level and nothing else. Leveling helps you kill better, move faster, make better weapons, etc..
The cutscenes are above the curve in this and you can get a good feel for the characters. Chuck can pick up and use hundreds of items in the game world and the powerful weapons are made by combining existing items. To be blunt, there is a lot of stuff around for Chuck to use.
There are two types of enemies. Zombies and humans. Zombies are bags of meat that you pummel. There are a lot of zombies. There are a lot of zombies. There are alot of zombies. There are mountains of zombies. Get it? Humans are psychopaths or looters which can give you headaches if you are not prepared for them. Chuck has different attack animations based on what weapons you are using. DR2 is robust in this regard.
The big game mechanic that may throw new players is time. Time is limited and you will be spending a lot of time rushing to different places to try and do everything. Where you then will wait while some idiots hug each other in the middle of a zombie attack so you can escort them to safety. The game will give you that "rush rush" feeling which does keep the immersion high.
Port quality is solid. Performance is solid. Story is decent and the cut-scenes are nice. Zombies die ugly and body parts go flying. Here are some pics.