The Praetorian guards provided a quick solution by murdering the Princeps but in so doing they set a bad precedent, which would be repeated over and over again.
Galba was a straight-laced disciplinarian and his failure to sufficiently reward legions who had rebelled against Nero and the Praetorian guard soon made him unpopular.
In addition, he was made 'protector of the imperial office' and became praetorian prefect in 73 AD, holding command of the praetorian guard and thus responsible for the Emperor's security and for security in Rome more generally.
His legacy is clouded by the excess and indulgence he displayed prior to becoming Emperor, and by the somewhat thuggish nature he displayed when he was praetorian prefect and in charge of the security of his father's regime.