NecroVision is noway as good as Painkiller, but it is sure satisfying, and i might say i liked it more than Painkiller Overdose!!!
Overall i was not disappointed. But most things fail in comparison with
Painkiller Battle Out Of Hell:
1) slower movement speed and choppy physics
2) worse graphics
3) lags more
4) stupid secret collecting system, can't return to begining of the level
5) annoying and repetetive letters
6) bad voice casting
7) mediocre level design
last boss Mephisto simply sux
However what makes it good: nice monsters, good "changing and adapting" gameplay, changing from one gameplay type to other in different levels, double gun system, fatality combos, vampyric artifacts, those increase your power + make collecting secrets a useful and important thing, new attack modes, spells and upgrades after beating challenge rooms - the most awesome part of the game!
If i had given original PK + BOOH a 9 out of 10, Necro would get 7 out of 10, PK Overdose would get a 6, and PK Resurrection would get a 1.