weaknesses and strenghts of PG

I am researching an advocation paper on Postgres. Basically I would like
to make a list of the most important strengths and weaknesses of
Postgres compared to a couple of other major databases.

The aim is to have a factual technical background for when advocating
Postgres to potential users.

Specifically I would like to compare:

- PG
- MySql
- Oracle
- MS SQL server
- Firebird

the facts I am looking for is about the core functionality and
application use aspects, while

the answers I am looking for, is for example whether
- one db more or less suited for GIS or warehouse or ...
- one db is not well suited for performance operations
- if there are types of operations a database is not good at,
   or conversely, is extremely good at.

No DB can be the best on all application types, so my focus is on
figuring out where PG is better than other DBs, where it is not and
where it is evenly matched.

regards

thomas