1) This is just a quick assessment based on one casual viewing.
2) Primeval is no worse than a lot of British TV drama, it's just that its got CGI dinosaurs in it so unlike other programmes I don't fast forward through most of it.
3) Without an exhaustive and frankly pointless analysis of every draft of the script it's impossible to say whether the poor script was the result of writer incompetence or down to gibbon interference -- however, my money's on the gibbons.
4) Primeval is a complex production and many of the poor acting, shooting and editing decisions could well be beyond the control of the production team, lost light, failed sfx etc etc. Therefore I'm going to confine myself to the broad structural problems with the script.
5) I'd have done the story differently but for the purpose of this blog I'm going to assume that the basic story elements were dictated by the producers.
6) The Idiot Ball was passed around with such speed that at times I thought I was watching the rugby - far too many instances to go into in this blog.
The script's principal sin is its failure to support its own turning points, particularly the revelation at the end that Abby and Connor lack the military background to do front line field work.
The ARC is not portrayed as militarised in any way, leaving aside the costuming and prop failures, just throwing in a few ranks or some military slang would have helped.
The turning point into the final act is really confused, Abby and Connor arrive back through the anomaly (the script misses the chance to ramp up the tension by having them do it in the nick of time before it's sealed) hug interchangeable action guy, then Connor manages to unseal the anomaly by accident letting in a dinosaur, then there is running around, then the dinosaur eats the anomaly device thingy and vanishes. And then we go back to the ARC to introduce Dr Bashir (Alexander Saddig) and the mini-skirt nerdette and the revelation that they're going to be confined to back room duty.
Connor says that the only thing that was keeping him going in the Cretaceous was the thought of coming back and doing the work but there's no hint of that when we see him in the Cretaceous (he's desperate for frothy coffee instead). Again the turning point is not supported by the rest of the script and so Connor's protestations, despite the best efforts of the actor, lack any resonance.
It's not like it wouldn't have been hard to fix:
Tense action sequence split between Abby and Connor trying to escape through the anomaly and the ARC responding with military efficiency.
Connor and Abby make it back through the anomaly meet anodyne action guy, hugs, anomaly is plugged (or whatever the spiky gun thing did). Back to...
The ARC: things seem different. Meet Dr Bashir who is (sinisterly) interested in future tech device. Revelation that the woman from the last series has died off screen(1). We have other little character options here, Anderson (the replacement maverick character) could have been unimpressed by Connor (still recovering) or funny little moments as Abby and Connor get used to the 21st Century again.
Then we ramp up the tension. Anomaly begins to unseal (or whatever), battle stations as the ARC scrambles again but Connor and Abby are left behind. Connor wants to seal the anomaly with the future tecbno thingy but Dr Bashir resists (he wants it for his multinational of evil) .
So Connor and Abby steal the device, confrontation in the arena, S-club 7, etc.
Back to the ARC to find that they are still demoted to back room jobs (particularly since they lost the future time device thingy).
That's a better structure which I knocked up in ten minutes, it's not the only solution -- any half competent screen writer could have come up with their own in a similar period of time. Since I know that the producers have access to, and the wherewithal to pay for, competent screen writers one has to ask...
Why was this script so poor?
(1) Instead of that terrible 'as you know bob' scene in the corridor. I swear that even George Lucas couldn't have written any thing that bad.