@Ali Akhaddar. I can't review scientific papers other than in my specialty or frontiers subjects with other specialities where I can have real expertise and pertinence. Maybe if I am only asked to review the methods, the statistics or overall conclusions. But not the scientific value.
Unfortunately its a common case, when it occur with me, am always apologize to the editorial board of the journal and correct my special line of research to them for future assistance...
In my opinion good to take the challenge, if of course it is within your interest. Because, firstly, you will get chance to read few topics out of your routine work and get knowledge. Secondly, a good work is the one which any person even out of the area could read and understand the concept well. The specialized person in that area may not catch few of the lacking information which might be cached buy others. Overall, a good review process would be the one which contains both reviewers, specialized and non-specialized one!