In a nutshell
Generally regarded as one of the worst characters in the game, Hsien Ko is a character that you really need to work for to win with. She has a pretty good assist and alright keepaway, but is really slow and very awkward to use.
Note that the amount of hits of Houten Geki affect overall damage scaling. The version may do more damage, but since it hits more often, it reaches the Damage Scaling Minimum much faster.
Even though the first hit of Tenrai Ha is a , you can still perform another one afterwards due to the use of the spiked balls, or even sometimes adding a Henkyo Ki in between them for huge overall damage.
Her Rimoukon Hyper, though only lasting 5 seconds when she's on point, lasts indefinitely as an assist. Using her Senpu Bu assist is the best way to take advantage of her hyper armor, as it works well for both defensive and offensive purposes.