16personalities is Big5 dressed up in MBTI terminology -- yes Big5 has a good methodology, but it doesn't even try to measure the stuff that Jung was getting at, if you get an "I" on 16personalities that means you rank low on Big5 sociability which just isn't what introversion is. Big5, more or less, can tell you how other people, society in general see you as. You probably know that you're sociable or not, Big5 can give you a very precise place on the bell curve, and you may or may not know whether you're neurotic, which can be very helpful. But it just doesn't have anything to do with cognition, and Big5 results very much aren't innate, which Jungian types are supposed to be.

Overall, each time I see a type ending in -T or -A I automatically assume the thing to be a mistype. From my experience it's quite a bit worse than chance.

The avatars are cute though and the wider typing community has adopted them wholesale.