Google keyboard available from Google Play and brings six majors features.

Henceforth available, it will only work on devices running Ice Cream Sandwich or newer. This means Google won't need to worry
about pushing out an OS update to get new features and fixes to it.
Majors features include:
Gesture Typing with dynamic floating preview
• Voice Typing
• Next-word suggestions and current-word completions
• Dictionaries for 26 languages
• Advanced keyboard layouts
• Works across your Android devices (tablets and phones)
Therefore  you need 15MB of space free.