The obvious advantage is that the only thing you require is a computer and Internet access. There are risks involved, just as there are risks in any venture.
Similar to online dating in the USA or UK or Australia, etc., do you know who you are really communicating with?
Some of the biggest criminal undertakings in the world in regard to credit card number collection, especially on the internet, have been masterminded in the Ukraine.
However, the Ukraine is still very much a cash economy, despite its attempts to integrate into European and other international institutions.
Does she speak English well, or do you speak Russian or Ukrainian?
If so, then your communication may be easily established.
Then, you'll probably get a solicitation for a bribe.
It needs to be said that bribery is illegal, but in reality, it is extremely improbable that you will be charged with bribing a police officer.