Hoya cv. Rebecca looks like exactly like you would think a cross of lacunosa and obscura would look, like a mini sunrise or obscura. It will get the same beautiful color on the leaves when sun-stressed from obscura, but the lacunosa parentage brings the leaf size down quite a bit.
When happy, can grow quickly into a nice full plant. Growth is relatively dense and compact and the leaves stay small, so you can have an impressive plant that doesn't take up too much space. All and all a really easy and rewarding plant.
Note - We typically let our plants get established and fairly large before we give them enough light to begin showing sun-stress coloration. Ease them into more light as they grow and you will begin to see the color increase over time.