The LawnVigor comes in three parts: the base with three hollow tines, a middle piece and the handle. The bolts and all the tools are included, plus some extra parts. I put a lot of force on it and it didn't bend at all.
You step on it and it pulls plugs. As you keep pushing it into the ground, the new plugs push the old ones out, so you don't have to clean the tines by hand. It's a lot easier with two hands. Space the holes out; the listing gives you an idea of spacing.
Do it after rain, or water the lawn first so the ground is soft. I did my section in about 30 minutes. Don't work out the day before, because you'll be sore in places you didn't know existed.
The Walensee has the same three-part design, but it feels a lot cheaper right off the bat: the handle material isn't as nice and the metal is thinner. If the ground isn't saturated, the spikes bend. I think they know that, because there are extra spikes in the bag.
It is way easier to use. It takes much less force, and I breezed through a section with it. But it doesn't pull any cores. It just adds holes for drainage.
I compared them side by side. The spike section had less water than it usually does, but the core-aerated section was almost completely drained. If you only need to do a small section, the core aerator costs a lot less than renting a machine. For a big yard it's too much manual work; rent the machine or hire it out.
I expect to do this once or twice a year. I'd usually pay someone around $400 to come out. They do the whole yard, but that one section is why I'd call them.