Peligro911 and all...
Yes, it works very well, it does help to plan things out a bit
My setup is probably more complicated than most...
Master Apple ID = 2 iPhones, 2 iPads, 1 iPad Mini, 4 iPod Touch's, 2 MacBooks, iMac, Mac Mini, iTunes on 1 PC
Each family member uses their own Apple ID for iCloud on their iOS device, some Mac computers have multiple users and each user uses their own Apple ID when logged in to a computer (mostly and shared Mac Mini) for iCloud
I use the most devices and so my own ID is used on an iPhone, iPad, iPad Mini, iTouch, Macbook, iMac and Mac Mini, so all of these devices have iCloud data in sync all the time and I can use messaging across devices. To add to this, but works just as well, my wife and I use Google to sync our contacts and calendars (multiple including work) AND I sync and Android phone and tablet to the contacts and calendars. All these devices stay in sync with no extra software and with relatively few problems although I do back up every now and then just in case. The only difficulty can be if I am using my iPad to read and I get an iMessage and I have my phone with me and both are making noises and popping up with messages, then I need to decide which one to use to reply or can switch back and forth as everything gets duplicated on each....
There are a couple good articles I had found online that do a good job of explaining how it works and how to do it if you want some extra guidance, as well as a chart that can be helpful in planning out how to use each Apple ID and so you can remember who is using what and which one.
How to configure iCloud if you share an Apple ID | Macworld
iOS 5 & iCloud Tips: Sharing an Apple ID With Your Family