Unnecessary lazily-made cash grab, inferior to original in every way
A few bullet points I came up with within an hour of seeing it:
1. There's no likable characters. Not effort to establish them or reasons to sympathise with them. We get a few minutes of exposition about the schlub fathers bad career luck, that's it. "Hey, why bother writing a good story, everyone knows what Poltergeist is about already right?". The establishing scenes (moving in/seeing ghosts for first time/getting paranormal investigators in) is all done so quickly and uncreatively.
2. The dialogue is terrible, like the sceenplay was scribbled down in half an hour after a quick viewing of the original.
3. Did any of the writers actually bother to find out what G.P.S. even stands for? Or how it works? Let alone find out what cheap drones are really capable of. Apparently bluetooth can transmit between different dimensions, wonder what version they were on?
4. The parent's performances are perfunctory, the kids are all bad. The Irish ghost hunter is the only slightly-likable performance but that's barely enough and it's right at the end.
5. There's no attempt to put any interesting spins on the original story. Bolting on a (really bad) slightly alternative ending doesn't count. So damn lazy.
6. Absolutely none of the CG ghosts/effects are scary. The original succeeded in having effective scares when needed, but also effective humour too. This glaringly has neither. Hang on, i'm wrong....there were a couple of laughably-bad scenes, but not many of them either.
7. The whole thing has the cynical air of "Let's just get this over and done with as quickly and efficiently as possible so we can hopefully make a fair profit for minimal effort and expense".
8. Watch the excellent original and forget this rubbish ever existed.