It missed a lot of things from its prequel. It didn't feel like I was in the cockpit, the ability to look around in the cockpit has been removed. Also, the interior looks horrible in comparison to MechWarrior 3 where there would be all kinds of instruments lighting up, here, you would only find low-res circuit like surfaces and a car sized instrument panel. You can't move your arms indepent either, which also removes a lot of the battle experience.
The customisation of your mech is limited, you may, for an example, only place missile weapons in the left torso, and ballistic type in the right.
In MechWarrior 3, everything, including ammunition, could be placed in the right leg if you wanted to. You knew where all the parts of your mech were placed, and knew what parts to protect.
Something positive is the increased number of vehicles you'll be fighting, it just feels good to blow them up.
MechWarrior 3 felt more realistic.

MechWarrior4, including all sequels, wasen't what I was looking for.