I just spent a week on the MV Celebes Explorer in August 2015....had read many things written about the boat before the trip. Most of the negative reviews about the boat were accurate. The company reports that a new boat will be ready next summer (2016), but again, it looks like they have been saying that for the past 3 years. I found the crew to be friendly and mostly helpful, but there were very little introductions or information given, and many crew seemed to be mainly taking care of their own needs. Occupying one of the two cabins on the main deck whose toilets were connected to fresh water, I got used to keeping a bucket of sea water in the bathroom for flushing. The shower in Room 1 did not work, a drip, not even a trickle! I got one shower from it when the boat was cruising, but there was no pressure at all when the boat was still. I reported this to "housekeeping" and was told they would look into it. The air conditioning was all torn apart in our room upon arrival, which made for a poor start to find tools and pieces of air conditioner spread out on the counter and bed. I now see the tight turn-around time they have between groups, so it was a minor inconvenience for having working air conditioning for our full week's stay. Food was ok, but not much variety. Wish there had been more fruit or even a salad just once. No desserts whatsoever, so if you are craving anything sweet, you will have to go ashore in Mabul and find some snacks or ice cream. Diesel smell was present a lot of the time.
Probably the overall disappointment about the boat, was that it stayed anchored in Mabul for 4 of our 7 days, they said the waters were too rough to drive the big boat to Sipadan, so we had to get up early, have our breakfast and lunch packed for the day, and ride the speedboat 45-1hr to go dive Sipadan. We hung for SIs on Sipadan with the other dive resort groups who were out for the day, so the ONLY advantage of staying on the MV Celebes Explorer was that we had dive permits every day for Sipadan. (Given that there was a picnic table on Sipadan island labeled for the Celebes Explorer, I am guessing maybe this happens more frequently than is reported.) The diving is quite amazing/awesome, even if we had low vis from recent storms! Don't pay extra to do the two local dives on Sunday upon arrival -- the local sites we were taken to were completely full of trash. We were expecting Mabul dives, as Dive the World had advertised, but instead were taken to Siamil (sp) close to Semporna, where we were warned that there might be fisherman fishing with dynamite.