I had my open water course at Bigblue and it was a great experience.
The instructors are all well experienced and professional, the first day we didn't leave the swimming pool until when all of us 4 was ok with all the skills we had to learn.
The dives were very nice and I found the overall atmosphere/location/dive spots amazing!
Only bad thing: I have paid about 1500 baht for an HD version of the video and still haven't received it, 1 month after the end of my open water and after many emails sent, that have been left with no reply.
Sadly disappointing. Apart from this I would recommend it!