I think that Pence is a good choice for Trump's VP. One of the most common criticisms lobbed against Trump is that he does not have enough experience in politics. Since he has served as a governor, Pence has the kind of real-world political experience that some voters are looking for.
Yes, Trump should have picked Pence for vice president. While it does not seem like any choice of vice president will be able to counteract Trump's ideas for policy, Pence is definitely someone who can try. Pence is much more conservative than Trump, so we still would not see any hint of liberalism, but Pence being more conservative may keep Trump in check.
Trump postponed the announcement that he was picking Pence as his Vice-Presidencial candidate after the attack in nice. He made a good decision on his timing - for a change - but also he made a good decision picking Penc. Pence would represent a safe choice who would solidify the Republican base and is popular with social conservatives.
Indiana Governor Mike Pence has come out in opposition to some of Trump's policies, specifically the ban on Muslims entering the United States. It would be better for Trump to choose a candidate that is on board with all of his opinions and policies in order to run a more cohesive campaign. Adding Mike Pence to the ticket is an attempt to reach voters that are not on board with Trump' radicalism.