Superb race - you won't regret it!
I've done two out of the three they have put on so far - and hope to add the Classic (August) again this year but have other plans for June 
The water is crystal clear and been fine temperature-wise in the ones I have done. The organisation is brilliant and a really welcoming feel for first-timers to the distance.
They usually put on a 'training day' a few weeks before the race, including some time in the water there - so keep an eye out for that.