I enjoyed it- and I guess the whole bank vault thing made sense. I thought the time displacement device was destroyed the first time, but I guess not. Maybe they can explain that all Terminators and protectors were sent at the same time, to different time periods before the machine was destroyed. After all, Skynet could theoretically send back a Terminator to every second of Sarah's or John's existence, or even to kill Sarah's parents. It just gets out of control that way; they need to limit how many times the displacement device can be used. Also, I don't mind different actors for different T-800s; in fact, in the first movie, Reese's flashback to the Terminator attack inside the Resistance's base had a different actor (we don't see him TOO well, but he's Arnold's real bodybuilder friend Franco Columbu). If every single T-800 looked like Arnold, they'd always be able to spot him immediately. Better that Arnold T-800 is a sub-model of many different T-800 models.
Sidenote: I want to recommend the 2 novels by S. M. Stirling called T2:Infiltrator and T2:Rising Storm. They are a sort of "Sarah Connor Chronicles" in themselves, and feature a female bad Terminator called an Infiltrator.
Couple of thoughts here:
1.) I seem to recall Reese saying in T1 that only he and Arnold were able to get through before the device was destroyed. If Skynet had unlimited terminators to send, why not just send 100 terminators back to the same timeline? That doesn't mean there wasn't a second device though. We don't have a clear picture of what happened with the future battle, but I don't think its far fetched for Skynet to have created a second device or to have rebuilt it using its original plans. There has to be some other device out there in order for T2 and T3 to have happened. I'm not sure how they would wipe out Skynet anyway - seems like the tech would be there for its "essence" to move wirelessly to back up machines if it was faced with destruction.
2.) I'm perfectly fine with multiple 800 series models as well. If you just made one and they all looked the same, the resistance would be able to spot them as easily as a robot version. But if you had 10-20-100 different versions, you could keep doing the same trick over and over.
Its interesting to note that Skynet can't completely wipe out humanity at any time prior to its own creation or it would end up erasing itself from existence. What I don't get so far is the mention last night that Engineers were sent back in time to build a new device. If they can do that, why not send terminators back in time and have them focus on building skynet instead of hunting JC?