You obviously haven't read the thread much. If you had you would see that at times he has been massively overrated, to the point that he was going to our saviour.
As for injury prone I've seen very little posts indicating that.
The reason that people don't like him is that he just isn't very good. He is slow, his hold up is poor and touch is terrible ( as an example there was one instance last season he was centre of goal, edge of the box, the ball was played to his feet, and his touch sent the ball out for a throw in). Yes he may finish the odd chance, but he is just a poor man Darren Bent who needs them put on a plate. We need better if we want to go up.