Ah, so it's one of these tax-haven states which accelerates the global "race to the bottom" regarding corporations' tax rate? That's not a good thing IMHO.
It's clearly stated that the tax level is 20%, not a tax-haven at all. Estonia in general is very far from the ultra-liberal country it has been depicted in the past (especially by the US Republicans): it has average EU taxation, minimum wage, taxpayer-funded public healthcare, ...