Bethesda did a couple things right and then screwed up.
The good:
+ FO 1&2 had turn based combat, where you got minimal control over just 1 toon. Switching to FPS mechanics was the logical choice.
+ the original never was so '50s orientated as FO3, but this change made FO3 much more appealing and unique compared to other PA settings.
+ the art direction in FO3 is great (though the animations and 3d models less so).
The bad:
- this is by far the best writing and VO Bethesda ever did, but it is still not good enough (still I can forgive this, if Beth continue improving).
- as a shooter it is pretty weak and needs alot of improving.
- the challenge is poor, because of instant stimpack health in unlimited quantities (a flaw FO also had, but there it cost you action points=time atleast).
- there's little sense of progression as you can(and should) max out a weapon skill + repair early and you can also obtain the best stuff early on.
- valuable stuff is located all over the place, unguarded.