I think people are concerned about his ability as well as the price.
I'd think he was a poor buy for £5m let alone £25m.
He just isn't any good at football, his scoring record is terrible, I can't find an attacking player with a worse goals/minute ratio.
It isn't as though he racks up the assists either.
And for the argument that he makes chances but terrible finishing by others costs him assists - no. They measure this with a stat called key passes and his scores in this area are terrible as well.
However Koeman/Walsh are very respected and see £25m to be a fair price for what he brings to the team. I just don't see it. Obviously I hope he does well, like I hoped Kone* would work out despite thinking he was [Poor language removed].
*Kone has a goal every 366 minutes in his Everton career. Bolasie a goal every 700+ minutes for Palace. Half as prolific as Aruna Kone in an Everton shirt, let that sink in.