Hi! Welcome!
I haven't had a chance to play with it much beyond making some really basic toy examples, so I'm curious to know: when you say you can't get decent output, what problems are you seeing? Are you using custom templates?
(I re-categorized your post so that it comes up in the same channels as the [quiet] announcement of PowerPoint support in R Markdown — since this is so new, I think it will be helpful to keep all the related posts together)