Tokikofag here. Here's my impressions on Lan
Disclaimer I didn't got her whale weapon so I am mostly using a 3/5 of her gacha weapon and a 5/5 arena weapon.

Well, shit this was one big disappointment. Lan is very similar to Shiranui in the sense that she has long reaching wide normals and mixture of melee and projectile skills. Much like Shiranui Lan also has gimmick around clones. However whereas Shiranui summons hers as an independent familiar, every 5th use of a skill will have Lan summon her familiar and "echo" the skill at half damage.

Lan's key moves are very vulnerable, Descending Dragon Strike and Binding Barrage have flashy startups and cooldowns which leave her prone to take damage, and Suo Di puts her dead in the heart of danger. Tempest Formation while very quick, safe and covering a wide arc, it's also just as weak as it is fast. Storm Formation is her most damning move, as it's her source of healing and it requires her very open normal string to not just start but also reach later parts in order to get much out of it, which is improbable when you're facing mortal danger..

The star of her moveset is Be Like Cloud, Be Like Water, her 250% Crit damage blue focused skill. As long as you hold the dash button she will continously attack and deal damage whatever is near with super armor and reducing defense making it hit really hard with a consistent crit rate. It never ends and in VR it can be exploited for it's continous skilll based hits to proc stuff like White Feather Asuka continously, however this will reduce it's damage significantly. It's weakness lies in that Lan moves slowly making it easy for enemies to simply walk away leaving you open to attacks, which will come at full damage as this move doesn't give you defense.