Direct and Negative:
* The reviewer offered harsh criticism of the film's plot.
* Her criticism was sharp and cutting.
* He voiced his criticism of the company's policies.
Neutral:
* The professor provided constructive criticism on the student's essay.
* The report included both praise and criticism of the program's effectiveness.
* She received critical feedback on her presentation.
Positive:
* The artist welcomed constructive criticism to improve her work.
* Her criticism was insightful and helpful.
* His criticism was well-founded and fair.
You can also use adverbs to modify the impact of the criticism:
* Warmly offering criticism
* Harshly criticizing
* Gently providing feedback
The best way to phrase criticism depends on the context and your desired tone.