Someone from Snooty Sims got their delivery of the Prima Guide early, and have written about it
here.
Some of my favourite bits:
Pay rises don't stop when you reach the top of a given career ladder. Keep at it, and every time your performance meter fills, your Sim gets another raise. By this little perk, it's worth it to keep at a job, conceivably, until you kick over and die. Elder sims are no longer forced to retire. You can keep right on working until the Grim Reaper comes calling, if you like. Or, like in TS2, you can retire and live off of a pension based on your career and the career level you were at when you retired.
Death is final. But that does not mean they are necessarily gone forever. If you install a grave marker, your departed Sim will haunt the area around it, usually after around 11 PM. Ghosts can and will interact with objects on the lot, making noise and generally creeping out the living. Different sims have different reactions to ghosts or haunted objects, which ghosts may possess, causing chairs to levitate and things of that nature. Remember when I said death was final? Well, that's actually only 80% true. If a loved one dies and you have their marker, there is a chance you will get a call from the Landgraab Industries Science Facility. The scientists have found a way to reverse death! Choose the Restore Ghost option at the Science Facility to bring your loved one back from the dead. Sort of. It turns out technology isn't perfect. Your loved one is returned to you as a playable ghost. They appear as a selectable Sim, with all of the regular interactions and socials. They can develop skills, cook, and attempt to live a regular life in Sunset Valley. If the departed Sim is a young adult or adult, they can Woohoo and even Try for Baby. If a child is conceived, there is a chance it will be a Ghost Baby. You can actually start an entire ghost family this way. There is no mention as to whether or not ghosts have motive decay, but apparently they do get moodlets and wishes just like 'live' sims.
It also lists the known cheats.