I didn't like the sudden switch from the high musical voices to the terrible British accents. They don't have British voices in the game, it doesn't make sense to give them different voices here.
I could barely understand a word of what was being said over the "tube" voice effect. Again made worse by the unfamiliar, deeper voices. Yes I get they're robots and you're going for that voice effect, but you over did it.
What I DID hear was a redundant overuse of the f-word for the first 2 minutes. Really? Are you 13 years old? No I'm not offended yadda-yadda, but when the dialog is riddled with swearing and it's not even in context it really dumbs down the movie and takes away from the rest of the script that I already can't hear because of reasons mentioned above.
I was expecting this flash to be something awesome (because Portal is an awesome series) but ended up being severely disappointed by the lack of polish. 3/10 and 2/5. Sorry.