Not exactly. Transfiguration is all about exchanges. Things want to keep the shape that they're in, right? A mouse wants to stay a mouse. He doesn't want to be a teacup. So when you transfigure a mouse to a teacup, he'll always look a little like a mouse, 'cos that's what he wants to be. And he's always going to want to go back to being a mouse, so he won't stay a teacup for very long.

[He reaches behind him, somewhat absently, and tugs the blanket off of the bed toward him as he talks. With his wand, he severs the corner of the blanket--a silent invisible burn--and the same spell, then, to bisect that corner, so he's got two pieces.]

But a mouse transfigured to a mole, that might be easier. A mouse transfigured to a very tiny furry jumper--also easy. A blanket, transfigured to a mitten--

[He taps the severed corner of one bit of blanket, and it curls up on itself, rolls into a narrow tube--and then one end inflates, puffing up into a space for a hand--a tube for the thumb, sealed at the top--]

So easy it barely takes any work at all.