Models are unreliable. I agree -- they are often late for photo shoots, and sometimes never show up at all!
Yes, the models disagree. Their range of disagreement in their estimation of climate futures is between pretty awful and unspeakably horrible. None estimates a pleasant future.
Some skeptics conflate 'uncertainty' with 'ignorance'. This is the idea that because scientists are uncertain about some aspect [of climate science] they therefore know nothing about [that aspect], and any estimate of it is mere guesswork.