I don't think so in the general context, unles the relationship is close and you can say anything to each other without hurt feelings. Saying a person sucks is

I don't think so in the general context, unles the relationship is close and you can say anything to each other without hurt feelings. Saying a person sucks is pretty pointless without a detailed performance review, identifying a few key points to improve in the next span (of months/years) and keeping tabs on progress. Usually saying someone sucks in general is pointless demotivation and hurts feelings without purpose. Identifying specific sucky aspects in ones work and suggesting helpfull improvements is beneficial, if requested.