Glad I'm not the only one to dislike this stage.
The high ceiling and (at least fairly) wide edges would seem good for Marth to recover, but I find myself struggling much more to get kills here, especially against D3 and Snake, who are pretty tough to kill anyway. In my opinion, Marth needs to get some of those characters off and keep them off early, before the tide turns (such as MK, Snake or D3). If those characters can survive longer, that just means that Marth may end up having to work and get more hits in before both Marth and his opponent are at equal opportunities to kill eachother.
Against pretty much everyone else, I would say that Marth is good here due to platform control and being able to use the tilt of the stage to his advantage when edgeguarding (and maybe recovering).
So...in summary: stage is too big vs characters you need to kill early, but it's good vs pretty much everyone else.
I'm thinking 7/10. Could be 6/10. I feel weird rating stages.