WordNet sense 1 (worthy of being depended on):

dependable, reliable

WordNet sense 2 (worthy of trust or belief):

trustworthy, trusty

WordNet sense 3 (open and genuine; not deceitful):

sincere

WordNet sense 4 (lacking pretension or affectation):

unpretentious

WordNet sense 5 (habitually speaking the truth):

veracious

WordNet sense 6 (expressing or given to expressing the truth):

truthful, true

WordNet sense 7 (not disposed to cheat or defraud; not deceptive or fraudulent):

honorable

WordNet sense 8 (free from guile):

guileless