Why no text on the back like on SW and ESB on Coov's covers?
Aside from that, a bit of constructive criticism on it to make it more in line with the SW/ESB efforts:
- Change the back logo so there's no box around it, and likewise no "STAR WARS" - simply "RETURN OF THE JEDI"
- Change the spine logo so it's the same as the back logo, but with the same above change - no box, no underline and no "STAR WARS"
- Goes without saying: the text on the back
This would make the spines match, and keep the back of the cover the same style as the others.
What I mean for the logo is, just make it simply like so:

Keep the front logo the same. On the SW and ESB covers, the front logo was one style, while the spine and back logos were the same, yet different from the front, and ESB's spine/back logo had no border and no "STAR WARS," unlike the front, which had both.
Other than that - excellent work!