Well, that rifle there is a basic civilian model of the M4A1 Carbine. The only thing I would replace on that rifle is the BUIS (Back Up Iron Sights). UTG is not known for quality sights. I'd replace it with Samson or A.R.M.S.
I have a Colt set up very similar like that rifle. DPMS is good quality. I built a M16A4 clone off a DPMS receiver and parts. Good rifle, good company, good quality. Buy with confidence.