Hi Igotta,
Well, it's not vital to have seen Series1 before China Girl : there are a few carry-over bits of backplot, but they've both got a very different feel (based only on the opening episode you and I saw last week!).
Series 1: NZ rural setting, atmospheric, The Lake almost a character itself. (Does deal with difficult subject matter, though, too).
Series 2 - China Girl : obviously Sydney-based, urban, so far seems less distinctive and more like a regular crime drama. 3 yrs on. Bar Robin and a couple of others, mostly all new characters. Totally separate case they're dealing with. (Obviously still difficult subject matter, as you'll have realised last week).
Am tempted to say stick with Series2 first (week-by-week, with us?!), safe in the knowledge that there's a quality series to watch afterwards.
But others would disagree...
Could link you to a "Quick rundown of what happened in Series 1"...or just Google...but then there'll be major spoilers for you.
Sorry, not much help, am I!
But I'm watching ep 2 tonight, believing it will improve, as have been told.
TBH, Elisabeth Moss's acting draws me in, even if it shows up everyone else's by comparison.
TL;DR:
Very different feel to Series 1...I'd save the original for after this.
Anything you want clarification on, skim this article (also week-by-week, so no spoilers):
www.theguardian.com/tv-and-radio/2017/jul/27/top-of-the-lake-china-girl-recap-episode-one-and-were-off
(Their TV reviewer liked ep1 more than I did!).