Main problem with Oracle is cost. They are changing the licensing structure for the standard edition which is going to have some major impact on our business.

Main problem with Oracle is cost. They are changing the licensing structure for the standard edition which is going to have some major impact on our business. Enterprise edition's price is completely prohibitive even for a large company. Most of the nice Oracle things require Enterprise. For example, RAC (clustering) actually works and is not bad, but to be useful you need Enterprise. The other thing that is pretty awesome is Enterprise Manager -- the web tool which lets you monitor your RAC, including looking at the executing queries, their plan and progress they are making. It is completely invaluable in diagnosing and improving slow queries. And it is, again, Enterprise only.