The coverup involved the missing minutes from a tape recording done in the Oval Office. Nixon was indeed guilty of obstruction of justice. This was after the break in had occurred and probably he was not aware of it untill after the fact. Poor judgement on his part.
It does however pale in comparison to what Democrats have done ever since.
Actually, no: the 18 minute gap in the White House tapes was never actually linked to President Nixon - his secretary, Rose Mary Woods, allegedly made some mistake with the tape that was never solved.
The main fact was that once the White House taping system was disclosed, President Nixon refused to destroy any of the tapes as his advisors had recommended. There was no "obstruction of justice".
If you really want to see Obstruction of Justice, try the IRS' wholesale destruction of computer hard drives and files - against congressional instructions - during Obama's reign - and Hillary's destruction of all evidence during her highly illegal use of a personal computer and server to transmit classified information.