As someone who’s placed diamond with him alone on the ptr, XQC has no clue what he’s talking about. If you play him right ie, behind cover and with your allies he is decent and strong like rein.

His primary fire is actually overpowered as all hell. You can shoot above and behind rein and orisa barriers to poke and get ult charge.

His ult if used right, ie throw your barrier slightly in the air then use the ult you can prevent ALL DAMAGE.

He is not clunky at all. He has one of the best kits of a launch character yet. Not overpowered but unique.