It is a fantastic swap!
You get to specify exactly what seeds you want to receive.
You get to pick from dozens of people's Have Lists. Some of those lists are HUGE.
If you list something rare or unusual in your Wish List, often someone will dig deep into their stash and send it to you even when they did not originally list it in their Have List.
You only pay postage twice: once going TO Ella and once coming BACK from her. And you can ask for 100 packets or more.
And it's on Cubits, Dave's "other free site".