I know many people who shy away from doing statistic in R for various good reasons. R is hard. Many of the things that make it great are things that only previously experienced coders can take advantage of. If you've never programmed before, learning stats in R means learning statistics and learning to code at the same time. That's nuts.

But if you're already comfortable with basic coding, R is wonderful. Still, the syntax is a lot to remember, and I have a hard time keeping it in my brain when it's been a few weeks since my last R analysis session. I use two wonderful resources to refresh my memory and learn new things:

1. Quick-R – While the site is branded as a way for SPSS/SAS/Stata users to learn R, it's really just the best all around resource for 90% of the analysis and visualization you'll want to do on a daily basis. The site provides great, simple explanation, sample code, and pointers to packages that have lots of shortcut methods.
2. R Wiki – The R-project itself has a great wiki with lots of detailed info. and code samples on many R functions. If it's not at Quick-R, this is where I'm going next.