I just read an unusual article, PostgreSQL at a glance, a lengthy, favorable review of a competing product by Kim Sung Kyu, Senior Software Engineer at CUBRID. The opening:
PostgreSQL shows excellent functionalities and performance. Considering its high quality, it may seem strange that PostgreSQL is not more popular. However, PostgreSQL continues to make progress. This article will discuss this database.
This is a good review of PostgreSQL, on CUBRID's blog no less. To openly write about alternative products speaks well of your own.