Yesterday I had a nice time delivering the SQLBI Methodology session at 24 Hours of PASS. A few hours later, I had the news about the official RTM of the PowerPivot book I wrote with Alberto. The complete title is Microsoft® PowerPivot for Excel® 2010: Give Your Data Meaning and we hope it will be a good book for both advanced Excel users (who are the primary target) and any BI developer/analyst who want to learn how to use this tool.
You can read the introduction in the Microsoft Press announcement. As you can see, DAX is a first class citizen in this book. Many users will not require to read more than half of the book (even if they will probably just copy/paste some formula from other chapters), but if you want to make complex models with PowerPivot, than you have a lot of examples and advanced models to investigate and learn how they work. Several times, the better solution is a mix of good model design, data cleansing and DAX expressions.
Now, I know that many people think that PowerPivot doesn’t matter too much. They work on Corporate BI and Self-Service BI is not an option in their company. Well, if you are using SSAS and you want to be ready when the next version of Analysis Services will be ready (maybe next year?), then you have to learn DAX. Learning it today with PowerPivot will put you in pole position when the new SSAS version will be released (and DAX will probably be improved). And if you, like me, have a strong background of MDX… well, remember the days you learned MDX? When you were trying to use a SQL approach hitting the wall of MDX difference? The same will happen with DAX.
Thus, take your time. You will learn the syntax of DAX in a few hours or days. But you will really learn how to use DAX in a few weeks or months. Well, I needed months, really. There were no documentation when I started. Now you have Books On Line, Video, Articles, Blog posts and, also, a brand new book! No more excuses now!