I had been looking forward to this movie for a long time. I'm old enough to remember (barely) the TV show. The fact that Blumhouse was producing it encouraged me. They've done strong work in the creepy movie space for years now.
The movie turned out to be weak on a lot of levels. As much as I typically enjoy Michael Peña, his performance had none of the gravitas that it needed. Instead of being the confident, powerful, physically imposing Mr. Rourke, he came across on-screen more as a bemused, doughy functionary reluctantly cranking out fantasies.
Structurally, the movie is a mess. They try to weave a macro-plot out of the combination of fantasies running on the island. In principle that's a fine idea, but because all of those fantasies were segregated from one another physically, what we got was a collection of vignettes that they merged towards the end of the movie.
They contrived some ridiculous synchronicity about how the fantasies were connected. I could forgive that if the plot-hole sleight-of-hand resulted in a fun resolution, but it didn't. Once the plot threads merged, the newly assembled Scooby Gang rushes to solve 'the problem' which I won't detail here so as to not spoil the movie for anyone.
A big factor of what made the individual fantasies and the final showdown so disappointing was that the Island itself had no animus. They wrote this script as if the island were an occult mechanism. Worse, they try to garner sympathy for Mr. Rourke. So, by the end, there is no antagonist per se because everyone is a victim and the island has been reduced to a mechanistic prop without any personality of its own. That made the ending more like a bureaucratic parsing of the island's occult framework rather than an emotional experience.
The way I sum it up is to say that the failure of this movie is an emerging pattern I see in Blumhouse movies. They excel at scene-level work, but are much weaker in weaving all that good work into something powerful. Consequently, what you get from Fantasy Island is a collection of occasionally evocative WTF moments, but nothing more.