I have been very pleased with my Last Straw Bottle Filler. I package in kegs and fill bottles for competitions, homebrew club meetings, or anywhere else I want to bring a small amount of my libation creations. Does the bottle filler improve my beer, probably not (I do like not having bottle dregs like I get with bottle conditioning). I would say to improve beer: Sanitation, Fermentation Temperature Control, and quality ingredients are key. But back to the bottle filler. Some say that it does not provide a good purge, but administering CO2 to the bottom of the bottle, to me would be a good purge. CO2 is heavier than air, so it is going to displace most of the air in the bottle. When you "purge" with the bottle filler, you can actually hear the bottle "filling up" with CO2 (think of filling a bottle from your refrigerator water. The pitch of the noise gets higher as the volume in the bottle increases). I enjoy using the bottle filler because I don't reduce the pressure in the keg (the bottle filler comes with about 8ft of tubing to reduce pressure through friction/head loss Don't shorten the length of the tubing). . I get my bottles ready and I fill them. Simple as that. No foam issues at all. Releasing the pressure on the keg first causes gasses to come out solution. Once that happens, filling is a nightmare.
Long story short, better beer? Meh. A very convenient way to package beer from a keg? Absolutely!