I must admit to being "old school" when it comes to Lisp coding. I like s-expressions. The loop macro introduces a non s-expression syntax to the language that I find a little uncomfortable. I spent 20 minutes this morning looking for interesting loop example uses and generally playing with them. Definitely some cool stuff, but I think that I will continue to pass on using the loop macro, except when it is already in other people's code - no point in rewriting stuff that works.
Different programming languages have different coding styles that seem to work well and are language specific. As an example, yesterday I wrote some Ruby code with two nested collection collect blocks. I had been coding non-stop in Common Lisp for weeks, and before I checked my new Ruby code into svn, I took another look at it: looked strange at first even though it was a natural Ruby coding style. I looked at it again this morning, after my "thinking in Lisp" mode was temporarily suspended, and the nested collect blocks looked just fine. Amazing how choice of programming language affects the way we think to solve problems.