One of the most popular beach in Langkawi, playing host to two of the most expensive resorts on the island, name the Four Seasons Resort and Tanjung Rhu Resort.
To me, the biggest attraction of Tanjung Rhu beach is probably the interesting limestone formations of the nearby islands. There are a number of small boat operators offering tours to the limestone islands - to see the vegetation, the dark caves, possibly some small animals, etc.
It is claimed at one of the islands, called Dangli Island, hosts some nice coral for snorkeling, but I have a feeling that the visibility is not so good, judging from the condition of the beach itself and its close proximity to the mangrove river that meets the Andaman Sea at Tanjung Rhu.
The beach is well kept by the resorts' personnel. Look up and see if you can catch a glimpse of the eagle roaming in the area, probably looking for a quick meal.