Magento – How to get product review details in Magento 2

You need to loop through all the voting options and create a rating for each option selected and like it back to your review.

foreach ($rating as $ratingId => $optionId) {
     Mage::getModel('rating/rating')
          ->setRatingId($ratingId)
          ->setReviewId($review->getId())
          ->setCustomerId(Mage::getSingleton('customer/session')->getCustomerId())
          ->addOptionVote($optionId, $product->getId());
}

To get all the ratings you can use the rating's resource collection:

    $ratingCollection = Mage::getModel('rating/rating')
        ->getResourceCollection()
        ->addEntityFilter('product')
        ->setPositionOrder()
        ->addRatingPerStoreName(Mage::app()->getStore()->getId())
        ->setStoreFilter(Mage::app()->getStore()->getId())
        ->load()
        ->addOptionToItems();

Then for each rating object you can call getOptions() to get each possible option for each rating.

You can try this

protected $_reviewFactory;

public function __construct(
    ...
    \Magento\Review\Model\ReviewFactory $reviewFactory,
    ...
) {
    ...
    $this->_reviewFactory = $reviewFactory;
    ...
}

public function getRatingSummary()
{
    ...
    $this->_reviewFactory->create()->getEntitySummary($product, $this->_storeManager->getStore()->getId());
    $ratingSummary = $product->getRatingSummary()->getRatingSummary();

    return $ratingSummary;
}

Or you can get $reviewFactory via ObjectManager (not the best solution)

$objectManager = \Magento\Framework\App\ObjectManager::getInstance();
$reviewFactory = $objectManager->create('Magento\Review\Model\Review');

$storeId = $this->_storeManager->getStore()->getId();
$reviewFactory->getEntitySummary($product, $storeId);

$ratingSummary = $product->getRatingSummary()->getRatingSummary();

hope this helps