Sketch is definitely a Product Hunt favorite. There are several Sketch resources and tools posted in the past several months. Search for "sketch" and you'll see.

Sketch has changed the way I design and prepare files for my team. I now can build and export assets for iOS, Android, the web, and even marketing materials in no time. It’s changed and improved my workflow exponentially.

how stable is it though really? ive heard it has some major bugs.

Still my favourite product design tool.