The Good
Reliable staining with quite quick incubation time, BV as a more "exotic" dye interferes less with "traditional" colors such as FITC, therefore these might be used for different stainings in the same tube.
The Bad
BV605 conjugate rather expensive, same clone available with different conjugations
The Bottom Line
As usual, BioLegend provides an easy to use antibody that works with the concentrations suggested by BioLegend. The unspecific staining of the CD45RO-negative cells might be an antibody or a sample-induced issue. Maybe a different antibody does not show this. Maybe more extensive washing is needed. This antibody is rather expensive because of the BV conjugation.