Yep, I went to Irian Jaya (Raya Ampat - 4 Kings) a few years ago and dived it for a month. I was on a small sailing/diving boat and we dived and visited also Kri Island where Max Ammer was located. The diving at Raya Ampat was fabulous : during my trip I saw everything from pygmy seahorses up to giant groupers, from epaulette sharks up to tassled wobbegongs (was even treated on a rare sight of about 50 grey reef sharks together), a tremendous variety of nudibranchs and literally countless species of fish. Most of the reefs were in very good shape with great lush soft corals, fans and hard coral gardens. There were some nice WWII airplane wrecks (P52?) as well. The schooling fish at some sites was mind-boggling especially when the current was running. Diving was often NOT easy though; plenty of current and some serious down-currents and "whirls" as well.
I really don't like comparing divesites with one-another and think the Similans, Myanmar, Irian Jaya, North Sulawesi, The Andaman Islands and even Peninsular Malaysia and Gulf of Thailand divesites all have their own sort of charm and are all worth diving. I for one still love the Similans, even after all those years diving the same sites over and over again.
Hope this will help a bit.