Rating - 4: worth reading multiple times (buy it)
I like Dilbert. If you do not, you will probably not enjoy the book. It is certainly not a 4 for everyone. Most people will read a strip, laugh or not, then not need to look at it ever again. I find Dilbert pretty consistently funny, and books of comic strips are perfect bathroom reading.
Dilbert can be hit or miss. Scott Adams acknowledges this. If you laugh at one strip a week, he calls it a win. It does not take many successes to make a worthwhile body of comic strips when you get another chance every day.
So that is all I have to say. You know what Dilbert is, so if you like it, this is more. If not, not. And if you do not have a bathroom bookshelf, this could easily be a 3.