I've never been into Valentine's Day. When I was single, it made me feel lonely and unloved. I didn't enjoy seen the pink, red, and white decorations all over the stores and I dreaded the day itself. Now that I'm married, I still don't see the value in Valentine's Day. We celebrate our love on anniversaries, and don't need an ordained love day. I have all the chocolate, flowers, and cards I need from Christmas, birthdays, anniversaries, Easter --- I really don't need more on Valentine's Day!
However, others have a whole different perspective: they enjoy the romance and gifts and warm fuzzy feelings. This could be a personality thing, or even a "how we met" thing (couples who meet over the internet may experience Cupid differently).
And -- I guess if you're stuck in one of the three stages of love, maybe you could use a boost like Valentine's Day. It could inject a little sorely needed romance and energy into your relationship - and that's never a bad thing.