I think Samus's punish game on Fox is severely weakened by the lack of platforms, because you can't platform techchase anymore. Samus can no longer use aerials to pressure Fox when he's on a platform, and aerials frankly are pretty bad on FD because you can't land earlier onto a platform (of course, aerials are often the only way to follow up certain hits, so you do them anyway... I guess upthrow -> aerial followups are more guaranteed now because there's no top plat to mess you up?).
On the other hand, if Fox gets Samus above him, it's now a lot harder to come down (Fox can just track your fall.)
In neutral, the fact that the stage is so wide sorta sucks for Samus: Fox has plenty of space to dd, to laser camp, and to gain run speed for deep/overshot aerials.
And of course, losing up-b OOS suuuucks. Your OOS options are now basically limited to "up-b and hope he doesn't know how to DI," or "wavedash oos and hope his pressure sucks." Yuck.