To their credit, the Shopify App store is much easier to navigate (and much more vibrant) than other e-commerce platform app communities. However I share your sentiment that "finding something good" is not always the easiest task.
There are a number of 3rd party app directories and review pages out there. One that I find well done is http://www.moblized.com/ which is focused on e-commerce. You can also check out some of the third party e-commerce blogs http://www.practicalecommerce.com/ and I find the folks on reddit to be able to offer really good advice most of the time as well if you check the entrepreneur and ecommerce subs.
And there is always Google I suppose.
Hope that helps
*full disclosure I work at an app developer
