My textbook says that despite the large electronegativity difference $\ce{BeF2}$ is covalent since the beryllium ion will have too much charge density and it will attract the fluorine electron cloud and therefore forms polar covalent bonds.
I looked it up on Wikipedia and found out that it has a crystal lattice, is soluble in water, and has a quite high melting point.
What else does one need to call a compound ionic? Am I or the textbook right?