Whether someone is 'nice' or not seems to be a common criteria in which people are judged by and approved or disapproved of. If someone were to describe an unknown person to you they usually start by labelling them as nice as if to give them some sort of stamp of approval as to what one will think of that person. However, being nice shouldn't necessarily be the fundamental decider on the preference of a person.
Firstly, 'niceness' doesn't determine the true goodness of a person. There is a difference between a good person and a person who does good things. Someone cab be an evidently nice person who seems cheerful, smiley and outgoing but who I feel may not have pure intentions or any depth to their cheeriness. They may be narcissistic or using their niceness with bad ulterior motives.
In addition, I have encountered many people who would't typically be described as 'nice' yet mean well, have few bad intentions or ulterior social agendas. They may not take such a pro-active approach to singular acts of kindness or have an obvious 'sweetness' to them. However, they can be extremely warm hearted, genuinely empathetic, and would stick with you throughout your troubles. The 'in your face' niceness as a criteria used to judge a person diminishes those introverted, socially challenged or troubled and damaged people who posses a warm heart.
Also, the more obvious 'in your face' nice facade can even sometimes be a sign of having to prove social worth or used as a means to an end socially whereas a genuinely good person would not feel the need to parade their niceness around and would let their purity speak for itself. The second approach is one that I trust more because genuine, pure and even silent intentions speak much louder than a facade of niceness or a series of supposedly nice actions and behaviours. A person upholding this approach will touch your life at many points due to their genuine concern and empathy for you, and not only when it is convenient for the 'nice' person.