Talking to Evan, apparently the installer used to show a summary screen. After a few observed issues this cycle (for example, bug 684309 and bug 813134), I think it makes sense to re-add the summary screen before the installer makes any destructive changes to the disk(s).
By providing a summary screen, the user is given a final chance to abort the install if they disagree with the heuristically determined installer strategy.
This summary screen should be displayed by default such that the user must click "yes"/"next" to accept the changes. This screen should also present a "go back" button to allow the user to make other choices.
The summary screen ideally would display both the existing disk layout and the proposed disk layout, for the latter showing:
- which partitions are to be reformatted
- which FS type each partition will become
- which disk the bootloader will be installed to
I feel that users would much rather be presented with a summary than have the possibility of data loss (perfect example of where the Principle of Least Surprise should apply I think :-)
I'd be happy to re-add this.