Bitcoin ATM is a lucrative investment if you can have the upfront huge cost to start operating it. Having one at a countries airport or shopping mall will attract a lot of users while you charge transaction fees on it usage.
But there is also something you need to be taken into account and that is the maintenance fees, not to mention that there's a possibility for the ATM to be vandalized by the criminals. Although as I've seen most of Bitcoin ATM charging quite the amount of fee but I just can't see that the Return of Investment will be near.