This is specifically using random picks from the BIP 39 word list. And there's a spanish version as well. If you're just picking random words from your head, it's likely very poor entropy.

But as anon posted above, I made a mistake in assuming that the BIP 39 seed phrase and the EFF long word list are the same. Actually the EFF long word list is about 3 times as long as the BIP 39 word list, and so the entropy is much higher with the EFF long word list.

I still think the BIP 39 word list is better because it's much more common and familiar. But, I'll definitely need to review the entropy numbers carefully before I include this as an exercise in my book MORE Bitcoin Hands-On.