Yes sir @ Sayar Ahmad Mir.. It could be very disturbing.. Although some reviewers waste time but editors should do more by giving deadlines.. Its a voluntary work but need to be done ontime
This is definitively not OK if the review of a paper takes one and a half year. During such a long time someone else could perhaps publish on the same topic. To me it shows that this journal is rather dubious / non-serious. Good journals should respond within 1-2 months.