It just reduces the trigger pull, so if you fire a lot of striker-fired guns you might like the galloway kit better.
However, if you have to ask, it probably won't matter to you. I'm relatively new to shooting and have no preference over striker-fired gun triggers and hammer-fired. I've shot the M&P Shield (striker-fired), SR9c (striker), as well as the LC9 (hammer), and all were superb guns. The firing mechanism and trigger action did not become determiners for what gun I chose.
edit: As for galloway's other parts, I'm not sure. I've heard both good and bad things about the recoil springs (better recoil, but higher malfunctions is what I've read across the 'net), and the steel guiderod is really inconsequential to how the gun functions