It is as invasive as a very invasive thing in a position in garden soil that it likes - naturally a woodland plant (it grows and flowers before deciduous trees leaf-up), and I suspect that it prefers acid soils - I never knew it on the basic clays soils of E Anglia where I grew up, but it is everywhere where I have moved to, on acid soils. It forms an impressive and somewhat depressing monoculture where it likes things - personally, I prefer bluebells, which are super-abundant around here, thankfully (so presumably no, or more likely, rather few muntjac).
DO NOT introduce it to your garden, leave it where it looks nice and naturally occurs i.e. elsewhere.