Doom 3 is its own thing, and it does it perfectly.
Those who try to compare it to the first 2 Doom games are coming at it from the wrong angle.
A "Doom game" is not built on gameplay alone, you need the lore to make it a "Doom game".
After all these years, this game still holds up pretty well, and you can even play it online for even more fun.
The flashlight mechanic is well done for the type of game that Doom 3 is, but, if the only version you can get is the BFG edition, then you can still enjoy it, though you won't experience it as it was originally intended.
If you're on PC, get vanilla Doom 3.
The BFG edition removed a level in Hell for Resurrection of Evil and changed a mechanic in a level.
The Lost Mission for the BFG edition can be had as a mod for vanilla Doom 3 as well.