I love Keynote for 6 reasons:
1) Awesome templates
Keynote has some very beautiful built in templates that look almost like magazines or movie posters. They also use some beautiful animations.
They are very easy to customize.
I never fail to get nice comments about presentations when I use them.
2) Auto correct integration
Keynote is one of the few slideshow applications that works with Mac OS's built in autocorrect.
This is a huge time saver, as it catches all your typos.
Of course, it can sometimes lead to muddled-up words. But Keynote also works with Mac OS's text-to-speech tool, so run it in that and you can catch all mistakes.
3) iCloud integration
Keynote is fully integrated with iCloud, so you can access your presentations on any system that has a browser. If using an Apple device, you can access documents via a native Keynote app which keeps things fast and snappy. For all other platforms you have to use a web browser, which is almost as good as the real apps.
4) It's free to use with free updates!
Keynote used to be paid for, but now it is free.
This is a big plus over Microsoft Powerpoint which is subscription based.
(You can also buy Microsoft Powerpoint outright, but then you don’t get new updated versions for free).
All new updated versions of keynotes are free as well!
5) Light, snappy and fast
A lot of Mac presentation software can be a little on the sluggish side. Keynote doesn't have this problem. It is fast and snappy.
6) Built in re-versioning
You can easily use the ‘Revert to’ command, to jump back to an older version of your slides. Back-ups are made automatically while you work so there is nothing to remember.
Key note has the following disadvantages
1) New updates are not released regularly
Apple normally only adds new features once or twice a year. This isn't too bad as Keynote already has everything most people need. But a quicker pace of new features would be great!
2): Spell checker is weak.
Spell checker often gives wrong suggestions. It’s too bad that it doesn't integrate with the Google spellcheck API as that never fails to give accurate suggestions.
Keynote is available for free, so you can try it out without any investment.
You can export all your slides in a variety of formats, so you don’t have to worry about being stuck in Keynote if you change your mind. But with all the great features Keynote has, you probably won't want to stop using it.
I use Keynote to make presentations.
I never fail to get praise about my presentations when I use Keynote as the slides and animations always look stunning.
The iCloud integration is excellent, as I can quickly make last minute changes even when I am not using my own computer!