As bad as parts of ROTJ are (they are many, and they are fundamental,) it still had the colossal achievement of beautfully establishing top-10 SW icons Palps and Jabba, awesome meme-ruling creatures like Ackbar, Bib Fortuna and Nien Nunb (not to mention a surprsingly long list of iconic creatures that have entered classic canon - Ree Yees, Squidhead, Klaatu, Amanaman etc,) iconic imperial costumes up there with the best ever (endlessly copied by later SW content) like Biker Scout and Royal Guard, iconic new craft designs like the Imperial Shuttle, speeder bike, Barge/Skiff and the TIE best-in-show, the Interceptor (and A-wings, and B-wings...,) fun/brilliant robot designs like EV-9D9 and 8D8, awesome visual worlds like Jabba's sail barge, Jabba's palace and the Emperor's DS stronghold, truly spectacular ATST action (brilliantly expanded from the cool, fan-fave Hoth battle tease), and a space battle that still ranks as one of the best ever put on film and a chase - the speeder bike chase - that gives the ESB asteroid chase a run for its money.
Just seeing golly-gosh good guy Luke Skywalker now all dressed in badass black (ready to take on Jabba's personal army - alone - then brazenly walking right into Palps/Vader's lair) and feminist icon Prnicess Leia chained in a metal bikini was worth price of admission alone.
Despite Ewoks, a mugging-high HF, an often matronly, pancake make-up and coke-nail CF, a valiant but sometimes out-of-his-acting-depth (and very-over-30 looking) MH, a less-than-stellar Vader outing (both story and suit) plus some truly silly plot mechanations (just try to figure out what the actual "rescuing Han" plan was) and even sillier twists that even the actors delivering them have difficulty keeping a straight face for (say no more...), well over half of ROTJ remains complete wall-to-wall sheer inventive giddy SW goodness on-par with or even at times exceeding the very best of ANH or ESB.