Went there in '09. Bad experience. They say all inclusive - what that boils down to is buffet breakfast and lunch everyday. Between 2pm and dinner, your only food option is nachos from the bar or room service appetizers. Dinner has to be booked every morning every day and the lines are long. You can only book one dinner reservation per evening, and the dinners weren't very good.
Only 1 type of beer. Mixed drinks are given to you in 5 oz plastic cups.
Rooms are nice and the pool is pretty nice.
Aruba is a beautiful place to stay, but for the $$$, the Marriott is much nicer. It's not all-inclusive, but there are some great places a short cab-ride away to eat. There is a Venezuelan steak house called El Gaucho that is amazing.
I've been to Aruba twice, both at the Marriott and Riu and I'd hands down stay at the Marriott. I'll never visit a Riu again.