1. Why C++ easy to write?
Designed fully describing itself.
Has equivalence with Lisp, the language somehow equivalent to the lambda calculus, the branch of mathematics describing Turing's model, at both compiling time and runtime. Many languages simulating Lisp at runtime, C++ as well as few languages mimic(1) themselves when compiling.
(1) see also: Boost::Phoenix Documentation.
2. Why C++ as effective as low-level codes?
Designed linkable with low-level codes.
Designed with control of direct low-level codes generation.
3.Why C++ portable?
Developed under its own standard.
4.Why some people dislike C++?
Of human's greedy, especially when there being a language rarely seen owning >=3 features as above.
Of human's laziness, especially when there being a language owning features as above, providing other features but not explicitly.
Of human's greedy and laziness, especially when there being a language owning its standard runtime library, with being able to reuse them in many amazing ways, with not satisfying everyone.
