Spent the May half term with my family (12/15) in the Lixouri Bay Beach Resort and we had a fabulous week. Imagine a week with all of the benefits of a (insert large tour operator) but none of the drawbacks. Lixouri Bay is a fairly small hotel/villa set - family run and incredibly welcoming. Rooms were very clean, looked newly built, everything worked and our small 2 bed apartment had a beautiful view over the beach and bay. Food was delicious although I'm now going crazy trying to find greek yoghurt in the UK which comes close to the standards in the hotel.
Where BeyondBeach is really set apart from the (larger operators) was on the beach. Really friendly and skilled team, great equipment and it NEVER ran out. I didn't once experience going to ask for something and not being able to get it straight away. There was never a rush for space on the beach either. Week rounded off nicely with a tremendously fun, if not very serious, mini-regatta.
I'd recommend picking up a hire car if you visit so that you can see more of Kefalonia - it's definitely worth it. The restaurants in Lixouri are well worth a visit too.