Names like "The Interchange" and "The 4-Level" are very telling; that interchange was the first 4-level freeway interchange in the world when it was built, so it being referred to with those names is evidence that it was considered a big deal and one of a kind back then.
Yes, the Pomona and Long Beach Fwy interchange is indeed a 4-level interchange, as well as the 57 and 10 interchange out in the Pomona area. The 57 and 10 interchange always seemed "beautiful" to me somehow, very swooping. I haven't been out that way in a long time now, but as a kid, when my family and I would go to Vegas via the 10 to the 15, we would pass that interchange, and it looked monumental to me somehow, I think because it seemed like it was out in the middle of nowhere, surrounded by nothing but vacant land. I wouldn't doubt that it's more developed around there now than it was back in the 1970s and 80s.