Without wishing to comment further on that particular report, I can offer a few tips for anyone who is asked for the first time to write an Part 35 expert witness report.
1. Be sure you are actually an expert in the area in question
2. Get professional training in writing Part 35 reports, meetings of experts and giving evidence
3. Remember always that your duty is to the court, rather than your client.
4. Offer evidence to back any opinions expressed in your report
5. Clearly differentiate between fact and opinion
6. Remember that name-calling is no substitute for rational argument
There is more detail in the first link.