Basicailly what do you think could be done to improve vats?
Visually its decent as is (though restoring the series groin target would help). Mechanically... The proximity based percentages should be replaced with the original linear difficulty progression (making certain high value targets permanently more difficult to hit ~put it back like it was in FO2).
Discard the current methods for VATS, and replace them with conceptually accurate ones. Make the VATS key drop the time scale of the game to about -? for the duration of the PCs APs; Remove the VATS invulnerability protection ~if you get hit, you get hit. Have it play out like this... Player presses the VATS key, and time slows to about 75% (or less ~tweak to perfection). In this mode the PCs APs are a count down clock, when they reach zero the time scale resumes to normal; any time they click the mouse to attack during this 'slowed time' the VATS menu pops up, they pick their limb target (here it really should be real-time VATS highlighting of the limb targets as they are moving, but I don't know if that's possible ~I think not; but I wish it were). The PC shoots, Vats ends.
Option:VATS could end with APs in reserve, or keep counting down until there are not enough APs to use the weapon.
Option 2: Pipboy access could be made only accessible during VATS at an AP cost while in combat. This would mean that during a fight, the PC cannot use the pipboy for healing or item access, or weapon switching ~except during VATS (as described above), and at a cost of APs (quite possibly
instead of an attack; if they don't have enough APs for both).