I did Tubbataha this year and due to extremely warm water temperatures the week I was there, we didn't see as many of the big-ticket items as others did. Our week had a manta and a hammerhead sighting but no whale sharks. That said, it was some of the most gorgeous, pristine, healthy reef diving I've ever done. Schools of fish exhibiting their natural behaviors, even fish that I didn't realize schooled (like a large school of coronetfish!??!?! which I had never seen); the most sharks on the reef I've ever seen diving (mostly grey / whitetips / silvertips), easily 10+ sharks per dive and some adorable schools of juveniles; barracuda schools and schools of jacks (that unfortunately were a little deeper/farther from us because of the intensely warm water); turtles galore; etc. Some of the sites felt like the Swiss alps of coral reef views, honestly, just some really stunning coral reef landscapes to see on our surface intervals.
It's pretty much all wall diving with plenty to see down the wall and on top of the reef as well. It's also more affordable than other liveaboards around the world imo. DESPITE some people thinking the week was a bust because no whale shark, it was a surreal beautiful experience and if I could afford it I'd go back every year. One of our divers had come back every year for seven years and had some incredible photos.
Oh and based on a quick look at Instagram for the LOB I was on, the other trips saw whale sharks, mantas, etc once the water was less extremely warm. I think we just had bad luck. I don't think it's as frequent as past years, but generally they expect one "big" sighting like that per liveaboard group.