To express personal opinion you can write:
- In my opinion/view...
- To my mind...
- To my way of thinking...
- I am convinced that...
- It strikes me that...
- It is my firm belief that...
- I am inclined to believe that...
- It seems to me that...
- As far as I am concerned...
- I think that...
To list advantages and disadvantages:
- One dis/advantage of...
- Another dis/advantage of...
- A further dis/advantage of...
- The main dis/advantage of...
- The greatest dis/advantage of...