you have a nice stomach it's very flat. With regards to critiscm I would say the long head of the triceps and rear deltoids could use some more focus. Also, can you feel your lats contracting? I think this comes as you get better w/the mind-muscle link. One thing that helps this area for sure is to retract your scapula before you do any pulling movements (pullups/pulldowns, rows). Another thing, you may need to lower the weight and increase contraction time on your pulls to really feel the muscle.