Legian Beach, where Double Six Beach is, is actually a middle point between Kuta Beach and Seminyak Beach. Double Six is just near the edge of Legian and start of Seminyak.
In terms of crowd, you can see less of a crowd here than Kuta Beach, although you can still see lots of umbrella lounges for you to sit and enjoy the beach. There are quite a number of surf schools here, so you can see some beginners trying to learn to surf. This area is definitely not for swimming as the waves are strong. But it's a nice place to stroll around the beach and hear the waves.
There are some warungs around the area too, where you can get some food. And there are a couple of bars just off the street parallel to the beach, if you dig the night life.
You can see locals selling their wares, but they are not pushy as I've read about. They sell jewelries, watches, kites. The kites were actually quite nice and intricate, I saw one they were flying which was a pirate ship with many sails. Actually I was just walking along, they offered 200,000 at first then even without any reaction from me except a smile, they lowered it to 100,000. I figured I could get it for 50,000 if I haggled, haha! But I didn't intend to buy it since it was too difficult to bring home anyway.
The sand is ok, but it's brown. There are also some garbage along the beach, plus patches of them along the sides, which is really a waste of the beauty of the beach. I don't mind the brown/black sand as long as the beach is clean. My friend told me Kuta Beach is even worse.
In the evening, you can see a lot of local folks who have come to enjoy the beach.
I was excited to see the sunset, unfortunately, it was raining that day, so I missed it. Instead, I had a walk under the rain with my umbrella on the pathway just parallel to the beach, which was also nice ;-)
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.