Well the owners also made them in the 50s and 60s. I don't see the 70's vibe thing. I can only speak for the 535 with regard to semi's, pretty awesome. Their specialty in my opinion are semis and jazz boxes. Although the solid bodies are nice too.
I bought a new one in 1995. At the time , I was looking for a Gibson 335. I could not find an older one and the quality of the new ones were not very good. A friend turne me on to the heritage which I found to be far superior in quality, playability etc. at that time. It is my "go to" guitar and love it. The best part is that it was $1300 with case (out the door), compared to a new Gibson which was priced around the $2000 range.
They make great guitars. The 555 is like the g es355, it is all maple construction though sometimes there will be one for sale that was customs made with a mahogany neck but that is rare. It is also fancier than a 535 (335) as well. It good for blues, jazz and rock and roll like most semies.