Is it plagiarism/OK if I use big parts of someones literature review for the introduction section of my paper?
If you copy the review text from the web into your own thesis it is a clear case of plagiarism. 

When you write academic text where there is a need to provide the sources for your information (as references) you need to have read the sources. It is not ok to quote sources without having even looked at them. In very rare cases, may it be acceptable to quote a source quoted by someone else in a publication. These cases may include very hard to find literature or literature in a different language. But, such secondary references should not be used unless deemed absolutely unavoidable.

If you need to cite the on-line review, you will need to look at how web-sources are cited at your school (if they are allowed). you can also look at the recommendations at American Psychological Association (APA; very appropriate for you) and their style site. You may find many other bits and pieces that are of interest to you.