Alright now I'm home, so here's my little 2 and a half cents.
Zelda definitely has a good camp game, not quite ours, but still good.
Din's Fire has some godly range, a quick one can hinder our approach.
A well placed retreating zair can avoid this problem.
If we try to be too offensive, she'll give us a retreating fair or bair to the face, that definitely hurts.
Just as Ravin said, it's hard to get an approach in, likewise, it's hard to land a kill, Zelda is a brick wall when it comes to that stuff against Samus.
That being said, knock her at a weird enough angle to where she can't recover, or cp a stage that she can't recover very well on.(Samus is okay on Final D, it really just depends on the character, it's not too bad against Zelda, but it's not too great either, I'd say go BF or, one of my favorites, the Mansion.
Mansion, you can bounce her into your smashes with tilts and aerials so well, it's beautiful.
And it's hard to kill you as long as you have that small ceiling to tech off.
Also I agree CPing PS1 is a good choice, due to the ledge.
Be careful firing your projectiles, definitely rely on missile stun to power shot combo if you want to land a fully charged b, you'd rather not take it back at you.
Try not to stay above her by any means, spiking should be a last resort at high percents.
If she gets you with her up air, you might as well not even DI, you're pretty gone.
Regardless of these downfalls, Samus does have some stuff going for her, Zelda is fairly lightish, so a well timed power shot, zair chasing off the edge, a spike if you're confident, should rid you of this princess. Abuse her sub par recovery, considering how weird it is to aim, they will have a hard time recovering if you send them in the right direction(Or wrong in their case.)
It is a little bit harder to juggle her due to her floatiness but you can still come back and win.
I'd say this match up is 6-4 Zelda at maximum, but my honest opinion is 55:45 Zelda.
I'd do Sheik too but I'll save that for another match up.