Horrible! Subtitled for dialogue that isn't English and British actors speak their scripts in English. It's too much work to casually watch. I watched the first episode and loved the plot, but don't look away from the screen or you could miss something vital to the story.

also find the constant shifting of languages jarring but I'm gonna give it another try. About to watch episode 2.

I only managed to watch the first two episodes. Couldn't bear to go further.
The serie lacks the ambition to do something great. Instead they focus on simplistic clichés, some action scenes and few good actors. The problem with those is that they are not given good situations and good lines to play.
That's really difficult to understand since both Canal+ and Sky manage to make great shows on their own. But every time I see an "International" serie, it's a dumbed down version of what each network is capable of producing on it's own. A good idea that ends in a waste of time and money.

Plus I tried to watch this show in French, but the dubbing is sooooooo bad ! The mix of french actors with others from differents parts of Europe, each one playing in different language is really disturbing.
I suspect the problem is the same in the english version.

Just finished this show. Nothing exceptional but not bad either. Indeed some clichés, but the plot was interesting enough for me to keep following.

The shifting in languages didn't bother me that much, with subtitles on no problem. But I guess it depends a bit on where you live.