Before I saw "Sunflowers" - or at least one of the four paintings - in the flesh as it were I had only seen reproductions of it on postcards, biscuit tins, umbrellas etc.. and I was rather underwhelmed by it as an image.
However seeing it in situ it - as did most of Van Gogh's work - took my breath away, The energy of the brushstokes and the emotion he has invetsed in the picture really junps out at you. And the texture of the paint, thickly applied, gives the painting a whole new dimension. His work close up is visceral, emotional, quite amazing. And the hindsight of knowing his life and tragic early death adds to ones feelings about the paintings themselves.
However, what I really love about art is that it provokes a reaction - whether it's love or hate - and that , for me, is what I think the purpose of art should be. So for me I don't think you've missed the point. You have reacted to it in an emotional way. As to whether it is worth �54m I think it is priceless but there are other pictures loved by many that I wouldn't swap a bag of sherbert for!