Sweet, tonka, almond-like, dry, woody odour. Lactonic nuance.
Its strength is better understood when properly diluted (usually at 5 or better 1%, in ethyl alcohol; anyway it will not dissolve at more than 8%). I usually keep it at a maximum concentration of 1% (fragrance concentrate), otherwise, it will grow and tend to overwhelm other notes.
It is a standard ingredient in chypres and fougères. It forms the classic ambrein accord together with vanillin, civet-like notes and bergamot.
Tonka bean absolute is quite obviously more complex and refined, it has soft, woodier, bitter, creamy, hay-tobacco-like, dark facets.
I have not yet found a good replacer for coumarin at this time. It could be Acetanisole (but it is thinner, sweeter, heliotropine-like in character). I really like Bicyclononalactone (closer to tonka, hay and hyraceum).