Not sure if it is just me, but it doesn't seem possible to choose 24 hour time format; that's quite a basic localisation function, even within the UK..
I think it follows the Android system setting for time format. Try changing your setting there.
I can VIEW the Agenda in 24 hour format, but I can't make an entry with 24 hour format, I HAVE to use am/pm (which is ABSOLUTELY NOT how I am used to enter/think about time...).
Other gripes/problems, in no particular order:
- In month view I get a new item generated, without the possibility to enter anything in it, when pressing enter... (An empty entry at noon, but I seem to SOMETIMES get the possibility to edit it too.)
- In week view I see less lines/entries than there clearly is room for... (It uses about 60 % of the height I guess, and in portrait-view about 30%!)
- It displays only start-time in week-view (and probably day-view too?), and not end-time.
- There is no way of entering date with only the keyboard except with the arrows...

- The anniversaries in the box on top on the right hand side in week view are wrong (it shows January 1st and March 29th on ALL weeks for me...)
- I apparently have to install the "Planet Sync adapter" to view or make to-do's?? (WHY?
Don't really use them, so can get by without them, but still??) - The "crossout" (and I assume the other "special view"-features too) does nothing...
- There doesn't seem to be any difference between "Events" and "Day entry"?? (Doesn't really bother me, but what is the point then?)
- I'm not able to "navigate" completely with the keyboard alone, I need to use the touchscreen for some things
- There is no way to edit the entries made with "Holiday Settings". I would like to be able to at least translate them...
- I do not seem to be able to snooze an alarm?? And the notification needs to be "opened" by dragging from top of the screen to be able to stop it as well?? I am coming from Symbian, and I am used to notifications popping up on the screen (and almost any action silences them if they have sound, with the opportunity to snooze, reject, or whatever, after silencing it).
- It seems the toggles for displaying entries in current timezone are backwards??
- No possibility of marking several items for copy, cut and/or deletion??
I do believe the list is actually longer than this, but this is what I remember at the moment. There are things I like as well; the zoom function, the cut/copy/paste possibility and the week-view is more or less how I like it (except for the 30-60% usage of space and missing end-time ).
But the BIGGEST problem whit Agenda/calendar for me is that I haven't gotten my old calendar-data over to Android/Gemini yet... Anybody know of a way to get data from Symbian calendar to Android, preferable without syncing with something like Google Calendar. I will probably do it through Google calendar if I absolutely HAVE TO, but would prefer to sync, or transfer, something locally to just my computer. I did think I got it across by using a program to get the vcs-files from a backup, converting to ics (and then merging). But it seems most of my recurring events didn't come across properly. Haven't really looked at it to see if the problem is with the vcs-files, ics-files or the merging, but it seems I might need another approach.
(I haven't gotten my SMSes over to Andriod yet either, and I've got a few thousand... But that is a bit too much OT, so I'll find a proper post to add it to, or start a new one for that.)