1. Easier to setup
(with a single script from https://github.com/technomancy/leiningen)
2. Benefits of a lisp-1, with nicer syntax (fewer confusing parens)
3. Easier to get started with Emacs + swank-clojure + lein
4. Wealth of Java libraries
1. Can't think of any, unless you want Interface Builder and similar, or are desperate to program using call/cc or are in any of the above ways a non-beginner. drscheme is a nice counterpoint though, in that the learning enviroment could include a bit more hand-holding.
IMHO for those coming from ruby/python etc. Clojure is a huge win. With square brackets for function-args, if you turn off or dim parens (emacs has several options such as rainbow-parens) the source looks very much like python.
And with M-q and friends and sexp editing, it behaves better.