How long are each of the games?
FO1 is very short, FO2 is as long as you'd expect any RPG to be - ie. quite long. FO:Tactics... no idea...
Is the customization better than F03?
If you refer to the skills yes - if you refer to the haircuts no.
Does the turn based combat work well?
In general or compared to some other game's turn based combat?
It's pretty solid.
More than FO3 that's for sure.
Very challenging at the beginning but it gets easier once you get the hang of it.
Does the top down view effect how fun the game is?
Define 'fun'.
(For me yes... top down view=more fun
)