Neither I can't ensure that. "Madly deply in love" is a phrase that, as I see it, is extremely difficult to use.
I'm sorry, but I think it will be a bit hard for you to understand what I am about to say because, probably, I won't make any sense at all, however I'll try to explain as best as I could.
I don't know if they actually love each other with all their might, that is very difficult to ensure. Sometimes, for example, you think you deeply love someone, that he/she is your life and all that.
But then something, whatever, happens... and you realize the love was not nearly as strong as you thought so.
You still know you loved that person in a way, but you come to the conclusion that the feeling was not as powerful, and as strong you thought it was.
However, I am convinced that what Harry and Ginny feel for each other is not "siblingly"-love, friendly-love and it is certainly
not lust.
It is love, plain and simple.
Why am I so sure?
Because the way Jo has written this shows me a few signs to truly determine that it
is love.
* Even though Ginny never got over Harry, she never wanted to press him or stalk him (unlike, say Romilda Vane). She didn't want him to be uncomfortable, so she stayed silent and later on, tried to be his friend.
*Despite this fact, despite her decission to avoid showing interest in him that might make him uneasy, Ginny never (I believe) stopped trying to know as much as she could about Harry.
I believe she always knew some things about him, things that Hermione told her, things that she overheard, things that he told her... etc.
That's why I believe she has a decent understanding of Harry's thoughts. She knows or at least is somewhat aware of what to expect from him. Maybe she doesn't know some part of him, but not for lack of trying, and I believe she will get to fully know him. Unless she already does. Because she probably mannaged to uncover those secrets of Harry that she didn't know while they were together.
* When Harry is with Cho during OotP, Ginny advices him to go with her and talk her because she knows or thinks they've had problems. She wants him happy, even if it hurts her.
* Harry was extremely happy with her. Even if we didn't get the chance to actually read a lot of their romance, we saw some scenes that were very significant. Like the "much more macho" scene. I saw it as Jo's way to tell the readers: "look how happy is Harry, and look how little worried he is"
As "the Choosen one" Harry has had a lot of pressure. The kind of pressure all of the superheros have on their shoulders. And he has never been a "normal" person.
That is why this little moments make him so happy, because he feels a part of it, a part of the normal.
Everybody needs to feel, once in a while, that we belong. While Harry was with Ginny, he did. And that leads me to my last point.
*In spite of all that happiness, he decided to put an end to their relationship.
Why? because he wanted to protect her. Wrong choice? yes, maybe. But a completely un-selfish one (does that word even exist?

).
Had he not cared about her, he would have keep up the romance. But if he stopped to think about the possible harm she could take by staying with him, we can assume he does care for her.
And if he broke up with her, and decided to renounce to that happines he felt by her side, decided to sacrifice his happines, that only means he does love her.
I, for one, would never sacrifice my happiness for someone I don't love. And even less for someone I don't care about.
Those are my reasons to believe what Ginny and Harry have is love.
And I insist, I can't "rate" their love. I can't say "it is deep love" or "it is just weak love" or anything similar.
That is something that only time will tell.