Jimmy: Did you read my novel?
Sara: Not yet. People told me it was romantic.
Is it fine to use 'was' here? I suspect 'is' most suitable here, because that book still exists, so use of 'is' is appropriate. Another versions can be:
People told me it is romantic.
People told me it was romantic.
People tell me it is romantic.
People tell me it was romantic.
So..
People told me it is romantic.
=> Means that people told you about that in the past, you heard it in the past. It was and still is romantic.
People told me it was romantic.
=> Means that people told you about that in the past, you heard it in the past. And it was romantic, we don't know whether it is or it is not now. The only absolute truth is that it was romantic.
People tell me it is romantic.
=> Means that today, people tell you about that, you didn't hear about that in the past. It is romantic, but we don't know whether it was or it was not back then.
People tell me it was romantic.
=> Means that today, people tell you about that (the telling is a general truth), and you didn't hear about that in the past. It was romantic, we don't know whether it is or it is not now. Again, the only absolute truth is that it was romantic.
Shortly, every choice you provide above is correct, the only matter is that how you see them and understand them from the perspective of time and tenses. Of course, provided that you know exactly how to differ was and is, told and tell.
Either of the following is correct:
People tell me it is romantic.
People told me it was romantic.
The reason is tense concord: in situations like this, the tense of the subordinate clause or reported speech must match the tense of the main clause. The tense of the subordinate clause does not really convey any meaning on its own, so it doesn't matter whether the book still is romantic or not. The only semantically significant tense is that of the main clause.
