Yes reviews do matter. However you must know that in today eCommerce and web driven world not all reviews are genuine. Sometime companies post fake positive reviews. Sometime the competitors post fake negative review. So in many cases people get confused whether they should trust the review or not.
There are lot better and easier ways to check the integrity and quality of a merchant account provider.
- Look at the website and see if it appears to be professional and active.
- Check the blog and social media handles. See if they post content regularly
- Search for there affiliation. What brands and other companies they are associated with.
- Check if they are listed on the card brand website.