Tuples are really more akin to records, which name their fields. Because of that, I found many things quite difficult to do since I couldn't just return and work with a generic tuple type; read: (int, string) doesn't equal (int, string) because one is forced to name the elements and magically know the names of elements as well from returned tuples.
And multi-threading was just a mishmash of ideas, none seemed "blessed" or really 1.0 worthy (as of 1.0).
Those two issues aside, I really liked Nim when I tried it. Maybe the issues above aren't issues any more and I should take another look?