They look unbeatable for the $, but there are a couple of items to note:
It looks like they are bolted together, not welded, so they will not be as rigid as more expensive welded designs.
The fit of the spikes is often not tight with cast iron bases, like what it appears these have. Wrapping the spikes in teflon plumbing tape can help that.
That said, they are a super value. You can't get the best at this price, not even used.