DB2 = Stable, but limited. Fair documentation, what there is of it.
Oracle = Excellent features, but highly unstable. Exhaustively documented, but often incorrectly.
At least two days out of every week we have to tend to Oracle 10g, trying to revive the listener or get the Enterprise Manager to work. It's getting tiresome. DB2 is mostly set it and forget it. Sure, it doesn't do everything we want it to, but at least it works reliably. In Oracle's case, the recent patch fiasco certainly doesn't help matters.