Thanks for your post and comments, Samir. Physics for Maple 2019 comes with a myriad of enhancements.
Regarding Tensor computations, to mention but one that is quite powerful, on top of the previous simplification capabilities for tensorial expressions, an additional, new, simplifier is in place, using group theory to simplify tensorial expressions taking tensor symmetries into account. Examples of this new simplifier handling expressions not handled in previous releases are in the help page for what is new in Physics in Maple 2019.
Besides tensor computations, a tremendous push happened in Quantum Mechanics, with the introduction of tensor products of quantum states and coherent states, a rewriting of the command for computing Taylor expansions with respect to anticommutative variables, and a new command for sorting the operands in noncommutative products in any desired way taking advantage of commutator and anticommutator rules that were set.
One of the most important things about what is new: there are three significant new documents in the help database of Maple 2019. One of them is this Complete Guide for Tensor Computations that you mentioned. The other two are the Mini-Course: Computer Algebra for Physicists, and another document on the Physics Updates. The latter has 77 descriptive links to the updates of Physics that happened for each release and the most relevant posts from Mapleprimes illustrating the package.
Last but not least, the number of changes under the hood is too large to itemize. One of them, not mentioned in the what's new pages, is that in Maple 2019 the impressive conversion network for mathematical functions of the system can now handle anticommutative and noncommutative variables, which are available when you load Physics.
Maple 2019 is one of the most voluminous releases ever in what concerns developments in the Physics package, regarding code, documentation and diversity of areas covered.
Edgardo S. Cheb-Terrab
Physics, Differential Equations and Mathematical Functions, Maplesoft
Editor, Computer Physics Communications