OK, so I guess this is a "Hitchhiker's Guide to the Galaxy"-based theme. I am not a fan of Douglas Adams, but I know many others are, and I hope they enjoy it. I do know that one of the "jokes" in the book is that the number 42 is given as the "answer to everything," and this is how JACKIEROBINSON, whose number was 42, and PRESIDENTCLINTON, who was the 42nd president, are worked into the THEME.
In non-theme material, I liked ECOCIDE (Environmental destruction) (although I don't actually like it, of course), SPLAYING (Spreading out), TUSSLE (Skirmish), and the O-rich oddity of TOOOLD (Like a 14-year-old vis-à-vis the Little League World Series). What a clue! And speaking of clues, I chuckled at "One hell of a writer?" for DANTE. Heh.
Onto the less-than-ideal heap I throw CORERS, TEHEE, OBLADI, and even SAUD (Mideast royal name). I'm not sure whether or not the two long Down answers are involved in the theme, but they both do, at least, share a "spoken language"-type clue - "'Peace out'" for SEEYOULATER and "'That's impossible!'" for ITCOULDNTBE. I guess they're ok, but they don't really do much for me. Perhaps the former could/should have been clued with "So long, and thanks for all the fish."
In the end, there's nothing terribly wrong with it, and I'm sure that fans of the Hitchhiker book(s?) will appreciate the tribute.