Hi Cardboardbox.
I've been here about a month now and have completed my Rescue Diver course. It's like a big family here at Mermaids, and there is always someone willing to help you out with anything you need.
As the guy from Aquanauts says, you don't just get chucked into strong currents straight away, and until you are comfortable, you will always have an experienced diver with you either as dive leader or buddy.
The Hardeep wreck does have quite strong currents, but you don't go there straight away (I did it as part of my deep and wreck adventure dives for AOW and had a very experienced instructor on hand with me and had a lot of fun!
So far I've seen lots of Turtles, Moray Eels, Porcupine Fish, Batfish, Groupers, Nudibranch, Blue Spotted Rays and lots more. So while the Vis is not always great, it does not stop you seeing plenty, and in my opinion it does help provide excellent training grounds. (If you can learn to instruct in Pattaya, you will be a great instructor in a lot of the places with more favourable conditions)
The food on the 4 Mermaids boats is excellent, and most of the interns live in one dedicated Mermaids Intern hotel (The Talay) which is quite adequate and means that there is always a friendly face to talk to or spend free time with. Wireless Internet is also free with Mermaids, so alot of the interns bring a laptop or netbook.
If you have any other questions, feel free to ask!