Learning R is challenging because documentation is scattered all over the place. There is no comprehensive book that covers many important use cases. To get the fundamentals, one has to look at multiple books as well as many online resources and tutorials. Jared has written an excellent book that covers the fundamentals (and more!). It is easy-to-understand, concise and well-written. The title "R for everyone" is accurate because, while it is great for R novices, it is also quite useful for experienced R hackers. It truly lives up to its title.
Chapters 1-4 cover the basics: installation, RStudio, the R package system, and basic language constructs. Chapter 5 discusses fundamental data structures: data frames, lists, matrices, and arrays. Importing data into R is covered in Chapter 6: reading data from CSV files, Excel spreadsheets, relational databases, and from other statistical packages such as SAS and SPSS. This chapter also illustrates saving objects to disk and scraping data from the Web. Statistical graphics is the subject of Chapter 7 including Hadley Wickham's irreplaceable ggplot2 package. Chapters 8-10 are about writing R functions, control structures, and loops. Altogether Chapters 1-10 cover lots of ground. But we're not even halfway through the book!
Chapters 11-12 introduce tools for data munging: base R's apply family of functions and aggregation, Hadley Wickham's packages plyr and reshape2, and various ways to do joins. A section on speeding up data frames with the indispensable data.table package is also included. Chapter 13 is all about working with string (character) data including regular expressions and Hadley Wickham's stringr package. Important probability distributions are the subject of Chapter 14. Chapter 15 discusses basic descriptive and inferential statistics including the t-test and the analysis of variance. Statistical modeling with linear and generalized linear models is the topic of Chapters 16-18. Topics here also include survival analysis, cross-validation, and the bootstrap. The last part of the book covers hugely important topics. Chapter 19 discusses regularization and shrinkage including Lasso and Ridge regression, their generalization the Elastic Net, and Bayesian shrinkage. Nonlinear and nonparametric methods are the focus of Chapter 20: nonlinear least squares, splines, generalized additive models, decision trees, and random forests. Chapter 21 covers time series analysis with autoregressive moving average (ARIMA), vector autoregressive (VAR), and generalized autoregressive conditional heteroskedasticity (GARCH) models. Clustering is the the topic of Chapter 22: K-means, partitioning around medoids (PAM), and hierarchical.
The final two chapters cover topics that are often omitted from other books and resources, making the book especially useful to seasoned programmers. Chapter 23 is about creating reproducible reports and slide shows with the Yihui Xie’s knitr package, LaTeX and Markdown. Developing R packages is the subject of Chapter 24.
A useful appendix on the R ecosystem puts icing on the cake with valuable resources including Meetups, conferences, Web sites and online documentation, other books, and folks to follow on Twitter.
Whether you are a beginner or an experienced R hacker looking to pick up new tricks, Jared's book will be good to have in your library. It covers a multitude of important topics, is concise and easy-to-read, and is as good as advertised.