Hint: If you are taking the bus E22, get off at stop ΛΙΜΝΗ and cross the street toward the white flags.
We went in the afternoon on a weekday in October and there weren't very many people. We were able to get a table with an umbrella which gave a perfect amount of shade and it was away from the crowd toward the middle of the lake. The lake is nice and clean, with some pretty flowers along the path to the ticket booth. Tickets were 8 euros for tourists/5 euros for locals.
The water wasn't as warm as we thought it would be, and I would expect it would be quite chilly if the sun wasn't out in full force. The water is also a little more salty that we expected. You are not allowed to use sunblock or sunscreen which is not good for people like us who are not used to a lot of sun and burn easily. My husband ended up spending most of the time on the shore in the shade. I really enjoyed the water and always felt safe. There are neat caves surrounding the lake. Although it was kind of annoying that several people kept going outside the roped off area to further explore the caves and the lifeguard had to keep yelling to get them to come back in because of the dangers of rockslides. Otherwise, it was a very relaxing and peaceful place where everyone pretty much kept to themselves.
At first, the doctor fish were too much. It was like intense tickling. They mostly stay near the edge of the water, so when you are swimming around, they are not near you for the most part. After watching many other people letting the fish surround them on the steps into the lake, I got more brave and finally was able to sit there for minutes at a time without shooing them away. But it is fairly easy to get them to leave you alone. They don't like movement and will swim away if you kick your feet. Also, I found the fish at the very last set of steps to be smaller and easier to get used to at the beginning. The bigger fish are deeper in the water (and near the more crowded sets of stairs) and the sensation from those fish is much stronger.
Besides not being able to wear sunblock, the only other major drawback was the service from restaurant. There was a menu on our table and we saw the waiters taking orders, but they never came by our table at all. Finally, I just went to the bussing station to grab some water, but saw there was a worm in the water pitcher. I couldn't see anywhere where you could go up to a counter and order, unless it was outside the gate where you scan your ticket to enter. Also, we never saw a dressing room or shower, so we just headed home.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.