He seems fairly solid to me.
-PROS-
-6f starter
-mid string that can break armor depending on the matchup
-good fireballs (air, high, low)
-great anti-air that leads to combo
-plus frames (1, 2, 22, b4, kameo)
-decent movement/advancing normals = whiff punishing
-Throw combos/loops
-corner carry
-easy execution
-safe strings with good stagger and no/few gaps
-doesn't have to worry about upblock punishes
-meterless damage/can save meter for breaker
-launching projectile (EX BF3)
-good oki setups (teleporting out of BF4, low hat jump ins)
-can convert jump in kicks midscreen (air fireball) and in the corner (full combo)
-CONS-
-relies heavily on kameo for throw playstyle (Kung Lao)
-lacks a real overhead/low game
-poor armored wakeup/reversal
-all specials are punishable
-IAFB doesn't consistently hit grounded targets
He lacks a lot of the dirt some other characters have but I definitely don't think he's trash. He has decent footsies in a series infamous for having almost no neutral. I think he could potentially be a really high damage meterless monster with Jax/Goro but I really like his throw mixup playstyle. I'm probably overlooking some aspects of his game but I've only been playing him for a day. Check out NinjaKilla if you wanna watch a good Liu. He's probably going to end up somewhere at the high end of mid-tier.