I loved The Western Guide to Feng Shui, but I was unsure what more the author could say in Room-by-Room. I had no cause for concern! Collins continues her breezy and easy to understand style of breaking Feng Shui into quickly digested pieces (in The Western Guide, it was Bagua regions, in Room-by-Room, it's the common rooms and exterior areas of a house). For each piece, she explains the basics of Feng Shui as applied in that situation, gives real life examples (both success and failure stories), and ends with a quick reference list for your later use. Room-by-Room also contains great color photographs that make the descriptions come alive.
Although The Western Guide is a better all-over explanation of Feng Shui, Room-by-Room gives you enough information to get started. Where Room-by-Room really shines is describing how to pick out the pieces to enhance the bagua areas. It is not enough to simply slap artwork depicting a naked couple in your relationship area -- if that area happens to fall in your entrance foyer, you'll be making guests uneasy with an overly intimate piece of art. If you're serious about giving your home a Feng Shui makeover, you should probably get both books.
The first guests I had in my home after its makeover used words like "cozy," "comfortable," and "homey" to describe their impressions of the house. Feng Shui really works!