NLP - Simple approach to identify commonalities in text comments between people
Note: The questioner requests for the response to be simple. Although this approach below is not simple, it is an attempt to provide a perspective that could help.  



Understanding the problem stated:
At a conceptual level, there are arguably 3 concepts in this question as given below.


Semantic similarity i.e. how similar the responses (in meaning) are to one another. In a way, this similarity could be loosely inferred as similar proposition.
Syntactic similarity i.e which aspects (tokens or entities or chunks) overlap between the responses.
Text classification i.e. "is one feedback in agreement with another or neutral or against?".


Evaluating approaches:
There could be many potential solutions. Following steps are one such attempt.


Step 1 Deploy a cosine similarity algorithm to measure the similarity between responses. In order to bring it a step closer to semantic similarity, use WORDNET to build the features for computing cosine similarity. This will ensure that tokens such as "path" are treated closer to token "road".
Step 2 Group responses (for the same question) beyond a threshold cosine value (example: 0.75) as similar responses. This can be loosely considered as a set of different responses for a question.
Step 3 Train a model to identify agreement or disagreement between responses. This training can be based on a classification algorithm or at the least based on a bag of words approach(hard coded tokens such as "i dont agree", "it is incorrect" etc). This step is perhaps the least scientific one but the only pragmatic one that the author can think of.