This is a topic that could occupy the rest of your day if you let it. Don't.
Here is the argument: "SAMR is not a model of learning.... SAMR does not relate to skills; it does nothing to develop the higher order skills of Bloom’s revised taxonomy: creativity, evaluation, analysis – the areas that we clearly need to focus on and develop with our young people." SAMR (Substitution Augmentation Modification Redefinition) may indeed may be derived from RAT (Replacement, Amplification, and Transformation). But the criticism is that SAMR lacks "a body of appropriate, peer-reviewed academic research, demonstrating the benefit of the SAMR model in improving outcomes for learners." Contrary to what the critics say, references to SAMR are to be found in peer reviewed literature - here, for example, or here, here, here, and on for several pages in Google Scholar (hard to find because 'Samr' is also a popular first name).
But all the above is pure straw man argument. Here's the real argument, as offered by Charlie Love: "the SAMR model degrades/demeans meaningful technology based learning activities and directs teachers to think of their use of technology as insufficient if it is not 'transformative'." And this version I've seen a lot. I've even used it. For example: "it is a waste of time and technology to simply use Second Life to recreate the classroom experience." Or "digital technology could be used much better than simply recreating flashcards for memorization." Against that Love argues, "the whole reason to bother with substitution/augmentation tasks is to gain the efficiencies of time, reduce the level of administration and reduce opportunities for learners to go down the wrong path." That's fine - but there is a ton of literature showing you can and should use technology to go beyond your original teaching task.