Important information if you are upgrading to FCP X and/or Motion 5 and/or Compressor 4
Installation Best Practices
Apple is recommending installing on a separate partition from FCP 7/Motion 4 but frankly I've been running FCP X/Motion 5 on the same boot drive with no issues, as have many others. Installing FCP X and the other apps does NOT overwrite your existing FCS apps - it just moves them to a new folder in your Applications folder.
Although if you do have Motion 4 and Motion 5 installed on the same partition, you'll run into this issue:
Motion Projects Cannot be Previewed in Finder or QuickTime Player
Not a deal-killer, but annoying.
Run Software Update After Install to Install ProApps QuickTime Codecs
You'll definitely want to to this.
Graphics Card Compatibility
You need an OpenCl-capable graphics card or Intel HD Graphics 3000 or later with at least 256MB of VRAM.
The link includes a chart of cards that do NOT meet the spec - of note is that the ATI Radeon X1900 XT, which used to be THE card for Motion (before the 4870 and 5870) is not supported.
Additional Motion 5 Content
You can download a content update that will add more Library content and sample media, but don't get too excited - it's all stuff that can be found in Motion 4.
Incorrect Alpha Interpretation
Easy to fix, but good to be aware of.
User Manuals
You can get the user manuals for FCP X, Motion 5, and Compressor 4 from the Help menu in each application or online - you can also print them to PDFs for easy offline access - I put my on my iPad to make them easy to grab.