[holymadness]

Shrug, it's $5. That's nothing. The cost of a crummy sandwich or two bus tickets. Even if it were a dud, it wouldn't be a tragedy. I wish people would put these things in perspective. They own a $650 phone but won't spend five bucks on an app they use every single day.

As for a preview, there are an insane number of screenshots, feature descriptions, and tutorials on the Marvin blog. More than I've ever seen for any number of comparatively-priced apps (Fantastical, Reeder, Twitterific, Articles, Dark Sky, etc.). It's pretty easy to inform yourself about what you're buying, and the developer has been very transparent about what he offers.

If you want good software, you have to support the devs who make it. Otherwise you end up with freemium crap, shovelware, or apps by massive corporations that ignore users and their requests.