Nice post. I've recently been trying to get back into R with the goal of being able to replace Excel. For the basic stuff R is great but as you start doing more complicated things it takes quite a while to figure out to do them in R. This is a part of the learning curve.
I really like Excel for adding up columns of numbers. Any task where you want to see the data (and the quantity of data is low enough to realistically be seen) and the operations performed on the data are relatively simple and straight-forward.
But once the operations start getting more involved, I really start disliking Excel (or any spreadsheet). Excel shows the data but hides the formulas. At this point, I very much prefer a script.
Something I've been thinking about is an Excel frontend with an R backend. Each worksheet becomes a data frame so you can edit it in Excel and quickly apply some formula but you can also jump into an R console to do something more complicated.
