We stayed in Afitos for 2 weeks in September and ate at Esteki about 5 times.
On 2 nights we did have to wait a while for a table but as has already been said it's a short wait and well worth it. This was at a time when many other places weren't particularly busy.
So what makes it so popular? Great food, again some times a little wait but it's worth it and at least you know it's been freshly prepared.Possibly the widest menu choice and there's always help on hand from either the lovely owner or equally nice and efficient waiter, if you can't decide what to have or if you're not sure what something is.