This tutorial takes you through 2 types of conversion.

From Test::More to Test2::Bundle::More

Cannot plan at import
use_ok() is gone (use ok ...; still works)
require_ok() is gone
todo_skip() is gone
eq_array(), eq_hash(), and eq_set() are gone
explain() is gone
new_ok() is gone
isa_ok() takes different arguments
is_deeply() has better diagnostics
$TODO is replaced by todo()

From Test2::Bundle::More to Test2::V0

is($r1, $r2) -> ref_is($r1, $r2)
is_deeply($a, $b) -> is($a, $b)

Must I?

Do I have to upgrade to Test2?
No. But it is a good idea.

Do I have to update my tests when I upgrade?
No in general, unless you use one of the tiny fraction of broken dists.

What dists are broken?

Log::Dispatch::Config::TestLog
Net::BitTorrent
Test::Able
Test::Aggregate
Test::Flatten
Test::Group
Test::ParallelSubtest
Test::Pretty
Test::Wrapper

Test::More

Bundle::More

Test2::V0