We visited the springs when we hired a jeep on holiday at the beginning of August and we thought they were fantastic! The water was really warm (even hot in places), the bubbles coming up through the rocks were fascinating and we didn't find the sulphur smell too bad.
We came back from Kefalos last week having had a fantastic relaxing holiday, staying at the Antonis Hotel (basic but very clean and friendly).
The views round Kamari bay are beautiful, there are lots of excellent tavernas overlooking the bay and we found everyone there to be really friendly. The beaches can be shingly but there is a small, shallow, sandy beach near the harbour which is ideal for children, or go to Paradise/Magic Beach. The water in the bay is crystal clear and you can see the fish swimming, even from up on the road.
It's worth the walk up to the Old Village, if only for the view over the bay. The walk isn't too bad if you take the short cuts but take a bottle of water with you - you'll need it. We found quite a lot of paths which led up from the resort to the old village.