I have a couple of Hoyas.
One was a cutting off my mother's plants (which, in turn, was a cutting off my grandmother's--her mother-in-law's--plant) which I've had since I was about 10. A veritable heirloom plant! It has dark green leaves with small pale flecks on them. Your plant is similar, but the leaves look a bit broader and more ovate than mine. I almost lost it this winter when our furnace failed--almost all of the plant was killed. It had one stem that survived and it's putting up a couple more now. The upshot is it probably won't bloom for awhile. The blooms have a really strong, but sweet, smell at night.
The other was given to me by a friend about 10 years ago. It's variegated yellow & green. Its blooms are also strongly scented, but not nearly so pleasant a smell. It is sweet, but there's another smell, sort of mixed in. It's vaguely like the smell of dust! Anyway, it sort of defeats my attempt at description. I'm wondreing if your plant is similar smelling?
If I ever get a digital camera, I'll post some pictures of some of these things!