Pretty good if you ask me, I thought it was kind of soothing in a way. However, just seeing the whole "Lavender Town Syndrome" theory pop up immediately kind of irked me. So, being a pokemon enthusiast myself sense I was a child (not into it as hardcore as I used to be) I do recall the effects of the lavender town syndrome. There are no proven cases of suicide linked directly to the game and in addition to that an additional research on the effect of the song showed the following results (based on what I found ages ago).
1) Only children under a certain age were affected (at the time I was one of them).
2) The syndrome was caused by the sharp sounds in the 1.0 version of the game.
3) In virtually all cases that there were headaches due to the syndrome, the only side effect was a headache.