The IPCC report has scientific underpinnings; it's not a predetermined result, but the reflection of continuing research. It's about the best we can do. Of course it's an approximation with errors, such is the fate of all models.
But to just point at a few short-comings, and do so with blatant disrespect for the context, and then conclude everything it says must be false is what I'd call unscientific. The linked article on wattsupwiththat doesn't even try to provide an alternative explanation. There have been skeptics who came up with reasonable objections and alternatives, but that article isn't one of them. It does falsely represent the 1.5°C threshold issue, though, to the point of manipulative dishonesty.
But to just point at a few short-comings, and do so with blatant disrespect for the context, and then conclude everything it says must be false is what I'd call unscientific. The linked article on wattsupwiththat doesn't even try to provide an alternative explanation. There have been skeptics who came up with reasonable objections and alternatives, but that article isn't one of them. It does falsely represent the 1.5°C threshold issue, though, to the point of manipulative dishonesty.