How hard wil be the migration from CI 2.0 to 3.0

[eluser]Pert[/eluser]
[quote author="anis2505" date="1371484203"]
For me as I sad it's almost the standard CI, I didn't found any problem just copy and paste and some little changes[/quote]

That's the beauty of CodeIgniter - from version to version it won't change that much, there are added features or feature enhancements and bugfixes, but the system itself should not completely change.