In short/in general:
– hard to play
– extremely team-reliant, even for support
– hard to be useful with his spells
– countered hard
+ I guess... challenging
+ everything unrelated to gameplay, his animations, comments, looks, movies, ads, icons, events

Q (heal):
– have to hit opponent first
– and then it still loads
– can't hit through minions
– it has almost unnoticeable damage on hit, during late it doesn't exist

W (knock-up):
– can be cancelled
– pretty long animation
– can't cancel the knock-up, in case we want to just use the dash

E (shield):
– due to it's dash moving Rakan behind the allie on use, it can't be cast if there are multiple enemies there, unless suicidal
+ very long range if playing with Xayah
+ made better, with other ads! (longer range, then before)

R:
+ easy to use
+ Looks amazing!?
+ Multi taunt
+ Increased Movementspeed (if you hit anyone)
– but only if you are close enough or able to get close enough asap
– allies often don't use the opportunity and just watch you dance