Hi all, first post here (probably last, not so much of a 'poster') but have been reading along this forum for some time, and while reading this post couldn't resist replying.
First time BMW owner (not counting my motorbikes) of a G21 for a bit over a year now, and while buying was torn between Tanzanite Blue, Portimao Blue and Citrin Schwarz (never seen that one IRL though). And it became TB, do not regret it because it is a stunning colour.
In sunlight very sparkling, but also in dark weather still very nice, almost close to black (which I always like as well).
The downside is indeed keeping it clean, you see everything on it. But on the flip side washing it becomes a very rewarding exercise :-/