What are the difficulties in data Warehouse development?

Recently, a friend asked, data warehouse development difficulties.

Do a few years of data warehousing, talk about Data Warehouse Technical Difficulties, I personally think no, what large data query and processing, Data Warehouse ETL process, these are not difficult,

The question is whether to think of the problem, take a large amount of data processing, now more and more distributed database vendors, Ncr/dwa and so on, can solve these problems.

I think the hardest thing about a data warehouse is to understand the business and the sensitivity of the business, how to make your project valuable, I think since you chose the Data Warehouse, you can't

Consider you as a 100% technician, you should be a 2 separate person, or less technology, data Warehouse application and promotion is the value of the Data warehouse.