Quite good SW performance for 3DS overall.. can't overlook KH3D's though, which has been incredibly bad.
A lot of 3DS games are holding up pretty well, but especially Kid Icarus, Miku and Harvest Moon. The triad doesn't count since we all know it's going to have big legs.
As a small comparison, which may not hold much value:
[PSP] Hatsune Miku: Project Diva - LTD: 187,558 (2009-07-02)
[3DS] Hatsune Miku and Future Stars: Project Mirai - LTD: 132.689 {2012.03.08}
It is not doing that bad. Still far from the releases that came afterward though, but this wasn't a fair comparison to begin with.
Another thing i'd like to point out
[3DS] Mario Kart 7 - 1.649.867 - Week 20
[NDS] Mario Kart DS - 1,288,749 - Week 20
MKDS first week below 15k was its 20th week, with 14,992 units sold.
MK7 first week below 15k was its 16th week, with 14,871 units sold.
Its legs are not as pronounced as MKDS' (by very little), but it had a much, much better first week.
If we wouldn't look at a weekly drop and sales would be about the same ratio (about 30% higher than MKDS) it would take around 117-120 weeks for MK7 to get to MKDS' LTD (which is on it's 170th week, at least on the latest garaph data).
Highly speculative and probably not worth much, but i felt like trying lol.
Edit: Feel free to correct me please D: