!!!SPOILERS!!! (Hell you've seen the trailer, so I don't know why I care?)
Rant Part 1
The people who wrote this movie have never watched T1 or T2. This is the
only possibility to explain this movie. Then again, they did reference several lines and specific shots, which leads me to believe they have some partial psychic sense (Which might explain why the characters they wrote also have psychic powers - see below). For example, they cannot have watched T2 because it does not contain the following dialogue...
John Connor: Wait a minute here. You're telling me that this thing (The T-1000) can imitate anything it touches?
The Terminator: No, it doesn't even need to touch it.
John Connor: Get real, like it could disguise itself as a pack of cigarettes?
The Terminator: Yes.
John Connor: Then why doesn't it become a bomb or a machine gun or something to get me?
The Terminator: The T-1000 can form complex machines. Moving parts.
John Connor: Like what?
The Terminator: The brain of T-800.
...and in the same way they cannot have watched T1 because Kyle says...
Kyle Reese: The 600 series had rubber skin. We spotted them easy, but these (T-800s) are new. They look human... sweat, bad breath, everything. Very hard to spot. I had to wait till he moved on you before I could zero him.
...but in Genisys Kyle recognises the T-800 straight away because either A: He looks like that Arnie Dude off the poster or B: He's bloody psychic. Again on the pschic front: How did Pop and Sarah know the original T-800's location when it arrived? I had that George-Lucas-Prequels feeling of them either lazily screwing things up, or doing it on purpose.
On to the terrible mis-casting... Emilia Clarke was actually worse than Jai Courtney. For, T2 Linda Hamilton famously trained for a year until she looked like she could punch through a brick wall, and did extensive weapons training with an ex-commando. Clarke on the other hand looked like she couldn't punch through paper. Obviously being a regular in Game of Thrones, she couldn't buff up... then why was she cast! She clearly was given
zero weapons/combat training as in her very first shot she is visibly flinching at the sound of the gun. Then for the rest of the movie she has no idea how to hold the guns and runs around nervously. These kind of details stand out a mile when they are not there. Jai Courtney is also totally wrong. Bland, cocksure, muscle bound and nothing like the established Kyle Reese and nothing like basic logic would tell his character should be like too.
The worst aspect was the dialogue: Kyle and Sarah in this movie were both smug, wise-cracking, sarcastic d*cks. They just spouted copy'n'paste dialogue from the garbage bin of lame Hollywood script writing. If the writers could not have written dialogue that felt less contected with the characters of T1 and T2 if they'd tried.
Random thought: Why in the nine hells did they not have the excellent Joe Morton playing Miles Dyson?!? Why was he recast?
Lastly (For now)... why is there a Bad Boys music montage! Arrrgghhh!