I personally enjoyed reading the article and found it very interesting, as I am just starting my professional career in BI.

I have however one small remark regarding a statement about debugging in the Staging chapter:

"Temporary tables are a fundamental part of the debugging of the ETL phase. When we detect an error, we will often see it in the OLAP cube. More often, the user will tell us that a specific number is incorrect when compared with his sources of data. What we need to do is to go back in the ETL pipeline in order to detect where we are computing that specific value and check the code. If we do not have temporary tables, we will not be able to verify the output of each step of the pipeline in order to find the wrong point in our project. We can only look at the boxes and arrows inside the data flow and think to what is happening there. On the other side, temporary tables will let us check the outputs of each step until we find the wrong one. We can correct it and – having the intermediate tables"

Since you are using the Microsoft BI Suite, why not use the data viewers in SSIS? The grid option lets you see the data in a particular flow between two components just as a temporary table would. This saves you the time and effort of creating those temporary tables for debugging and a data viewer is easily added or removed.