Except for the legginess, the rhododendron looks fine. I would not, however, allow the ground cover (pachysandra?) to grow directly on top of the rhododendron roots or even very close to them. Best way to rejuvenate the plant is to cut back about a third in the first spring, then pinch the growth tips that appear in order to encourage bushiness. Do another third the second spring, etc. This assumes there is enough light in the location. Rhododendrons in too much shade naturally grow leggy and there is not a great deal except constant pinching that can be done about it.