If functionality and stability are the criteria, LibreOffice's Writer is a more powerful tool than Microsoft Word.
But how do the other main productivity tools in LibreOffice and Microsoft Office (MSO) compare? In other words, how do Impress and PowerPoint, the slide show applications in the two office suites, compare? Or Calc and Excel, the spreadsheet apps?
The answers are far more complicated than with the word processors. Writer and Word are applications with distinctly different approaches and assumptions about how users work. By contrast, LibreOffice's Impress and Calc, which were developed after Writer, are designed for compatibility with their MSO counter-parts, and are more similar to them in design.
Nor does the LibreOffice emphasis on styles, which makes such a difference in word processing, matter so much in slide shows and spreadsheets. Both Impress and Calc offer styles, and they can be powerful tools.
But, unlike Writer, Impress and Calc do not require the use of styles for advanced features. Styles work best with largely uniform information layouts like text, and are harder to implement in more variable layouts like slide shows and spreadsheets -- which is likely why many Impress and Calc users ignore them completely.
Probably the most obvious difference is that PowerPoint and Excel use MSO's ribbon interface, while Impress and Calc, like the rest of LibreOffice, use traditional menus and toolbars.
Although this difference does not affect functionality, most users are likely to have strong opinions about it. While some argue that ribbon interfaces are more efficient, others argue that finding features on them can be harder, and that their dialog windows tend to be cramped. However, many users acquiesce with a few grumbles to whatever interface they are offered.
Instead, the majority of differences tend to be subtle ones, a matter of small bits of extra functionality more than basic features.
In most Linux distributions, Impress is configured to start with a wizard. This wizard guides users through the basics of choosing a template, slide background, and transitions, but can be bypassed at any time. It can also be turned off altogether by unselecting Tools -> Options -> LibreOffice Impress -> General -> Start with Wizard.
By contrast, PowerPoint opens directly on the editing window. On the left is a pane showing thumbnails of all the slides in the presentation. In the middle is the main editing pane for the current slide, with an impossibly small space below it for adding notes.
Impress's editing window includes the thumbnail pane and the main editing space, but not the notes pane. Nor can Impress group thumbnails into sections for group editing, the way that PowerPoint can.
Instead, Impress has a task pane on the right with tabs for various tasks. If unmodified, this layout more or less requires users to work with a maximized window, but has the advantage of making the commonly used tools accessible.
Assuming that LibreOffice has been packaged in a distribution with a couple of dozen background templates (or that you have installed a selection from the web), Impress and PowerPoint have very few differences. Both offer similar views of your work, although they are easier to switch in Impress, where there are tabs on the main editing pane. The selection of transitions is also similar in the two apps.
Both, too, support the same array of objects: graphics, tables, animation, sound, and video clips. Each supports diagrams as well, although PowerPoint offers a selection of playback buttons, while Impress offers connectors between parts of a diagram that keep the parts connected as they are moved about, and has Presentation Styles for managing objects in a diagram.
The differences only start to emerge with the finishing touches. Here, PowerPoint has a decided advantage, with the ability to record narration and laser point gestures, and to sync slide changes with a CD.