Imma Make it quick.
Amazing little boy who does amazing things.
Ekko pretty much has it all, cc, shield, gap closer, and TONS OF DMG.
i Suggest everyone to play this champ, it is amazing, fun to play champ.

Pros:
Has a gap closer
TONS of dmg
has a shield
has a good amount of cc (slow and stun)
can do a lot of outplays and outsmart (which is always fun)
His Ult (if performed as should) deal tons of dmg and can determine a win or lose of a teamfight

Cons:
has no good escape (he can use his E but Ekko dashes a small distance)
Hard to master
Hard to ult and hit all the enemies
requirs good predictions to deal tons of dmg and cc

with ekko u can farm pretty ez after buying ludens, all u need to do is to q the wave and wait for the money to come.
before u get ludens u need to and last hit the Casters and try to wait a bit for the front minions to reach low health

Well, basicly the use of ekko's ult can be for 2 uses:
1. escape, lets say u went into a teamfight, lost tons of health and need to retreat, all u do is pressing R to tp back to ur "copy" u will recive tons of health and teleporting far away from the teamfight
2. to deal tons of dmg to ur enemies (to nuke em) if performed right u can combo 5-man-stun and nuke them all, all u need to do is to retreat enough for u "copy" to stay near to them, then u have to predict where will they go (if they chase u you will use w infront of them) then after u W u ult and basicly right when the W slows them u get into the W's radius (which will stun them) and u will deal tons of dmg.