If you're looking for a minimal and simple calendar app then PinkCal might be for you.

Double tap a date to enter a new item. Single tap a date to view items starting at that date. Your selected date is shown in green. Items are listed under the calendar. Check out the screenshots.

Use the "early bird" setting, specified in minutes, to have reminders appear early.

Optionally upload to Google Calendar. Turn on 'sync' so that appointment adds/edits/deletes are sent to Google Calendar.