英语评论性作文的写作步骤如下：

确定评论主题

明确你要评论的对象，例如产品、服务、事件、电影、书籍等。

撰写引言

在引言中简要介绍评论的主题，并可以提出自己的观点或立场。

主体部分

优点分析：详细描述该对象的优点，可以引用具体事例或数据支持。

缺点分析：客观指出该对象的不足之处，同样可以引用具体事例或数据。

比较分析：如果可能，将该对象与其他类似对象进行比较，突出其独特之处或不足。

结论部分

总结评论的主要观点，可以提出改进建议或自己的最终看法。

检查语法和拼写

确保文章语法正确，拼写准确，避免低级错误。

示例结构

引言：

Recently, I have been using the [product/service/event] and I would like to share my thoughts on it.

主体部分：

优点：

The [product/service/event] has several advantages. For instance, [example 1], [example 2].

缺点：

However, there are also some drawbacks to consider. For example, [example 3].

比较分析：

Compared to [another product/service/event], [this one] has [specific advantage] but also [specific disadvantage].

结论部分：

Overall, the [product/service/event] is [positive evaluation] with some notable flaws. If [specific improvement] could be made, it would be even better.

示例

引言：

Recently, I have been using the new smartphone and I would like to share my thoughts on its performance and features.

主体部分：

优点：

The smartphone has a high-resolution camera with excellent photo quality, which is perfect for photography enthusiasts.

It also has a long-lasting battery life, allowing me to use it throughout the day without frequent charging.

缺点：

The operating system is a bit complex for some users, which may take some time to get used to.

The price of the smartphone is relatively high compared to other options in the market.

比较分析：

Compared to the previous model, this smartphone has improved significantly in terms of battery life but still lacks some of the features found in more expensive models.

结论部分：

Overall, the new smartphone is a solid choice for those who value high-quality photography and a long battery life. However, its complex operating system and high price may not be suitable for everyone. If the manufacturer could simplify the OS and offer it at a more competitive price, it would be an even better option.

通过以上步骤和示例，你可以撰写一篇结构清晰、内容全面的英语评论性作文。