From my point of view Kalavarda beach it is a nice place to swim! However, given that in Rhodes you can find many other heavenly beaches, Kalavarda is not highly recommended,
At the advantages I could state that is not crowed and you can find the hard beautifulness of the unexplored beaches.
Another great option for people staying near Rhodes town. Close to a picturesque village with the same name, Kalavarda beach is a beautiful sandy beach that does not get so crowded as other "city" beaches in the island. If you are staying in the area, go for it, it's one of the best, if you are staying in Ixia, Faliraki...