So, I have heard of the utterly abysmal launch of SotS 2 and it kind of dropped off my radar. But now I see it for 5 EUR with all expansions, is it worth it?

Not yet, in my opinion. My saves tend to become corrupted after a point, and there are a number of small flaws that add up after awhile. I recommend buying SOTS1 Complete, and waiting to see if Kerberos manages to release a 2nd expansion.