Easy UI, great customer service (we have our rep in India), good data quality - we can easily identify spam contacts from real people with this product! No major issues so far though I do hear some complaints about certain features not working as intended but nothing that's an actual show stopper yet like others mentioned here already before me :) We're solving multiple problems at once by using their API which helps us build new products faster than without having all those manual steps of building them ourselves first or doing lotsa research online beforehand :).