Write a script to classify the sentiment of a list of comments with Python.
comments = ["This product is great!", "I hate this product", "Not sure whether to buy it"]
def classify_sentiment(comments):
    results = []
    for comment in comments:
        if "great" in comment or "love" in comment:
            results.append("positive")
        elif "hate" in comment or "bad" in comment:
            results.append("negative")
        else: 
            results.append("neutral")
    return results

print(classify_sentiment(comments))