We booked with Smile and it was ok,the guide was very friendly and helpful,we give the Argassi Smile office positive feed back about her.
Good points-you get to see the island in a quick time,you can buy local (delicious)honey,olive oil,wine and good such as wall hangings/mats,also there are lots of stops so you can walk about,the Blue Caves Boat trip is well worth a visit and going in the small boat means you can actually get into the caves to take a good photo.
Bad points-you had to go to the cafe and resturant the coach stopped at,as it was usually the only place to eat nearby,and it was quite expensive (bring some sandwiches/snacks with you!),We spent a lot of time dropping people off in the resorts at the start and end (about an hour)it was ok if you were on the first drop off point!!
Also(this isnt the companies fault) we lost a bit of time and had to rush in the end as the same people kept being late and we had to wait on the coach for them!!Typical eh?