Pretty good but can use a few tweaks.

Good graphics and pretty realistic but
the scoring is confusing at first. Also,
one major flaw is that you pay out on all
losing hands even if you did not discard
the winning tile. This depletes your coin
count very quickly. In real games, you
only pay if you discard the winning tile
for an opponent or when someone
self-draws. This is actually part of the
strategy. Another feature that can be
added is your current hands point count
so you know if you have enough to win
or need to gain more points while you
still have the option to. It would also be
nice to see your flowers on hand. I dont
have the full version but maybe it
already addresses some of these issues.
For a free version of real mahjong, this is
quite good.

Mop43729 about Mahjong 13 tiles, v1.3