Is there excessive lubricant on my new rear derailleur?
All of that goo is very typical of drivetrain components that are fresh from the factory. The factory uses a particularly thick lubricant to protect the parts until they're purchased or installed (lest they sit on a shelf and risk being exposed to moisture).

Basically, the factory is expecting whoever installs said drivetrain components to identify any excessive grease (some of it is there for good cause, such as protecting the inner spring from the elements), wipe it down, and re-lubricate with something lighter!