I have written web applications in Ruby on Rails, PHP and recently Clojure. While I absolutely love Clojure and what it offers, building web apps with it has proven painful, because the library ecosystem just isn't there yet. There is indeed the foundation, as the author mentioned - Ring, the equivalent of Ruby's Rack, and a few other frameworks such as Compojure. But these are very early stage projects, parts of them are still being rewritten and they are relatively poorly documented as of now. If you run into problems along the way "how do you do this?" you would have a hard time finding adequate info online, whereas the amount of information that exists out there for RoR, for example, is incredible (message boards, tutorials, blog posts).
But even if you go through the initial pains of figuring out how things fit together, many tools are still missing. An easy to use templating library, for example. (several exist already but they are still early stages /are being refactored). Also things like the gems and plugins ecosystem in RoR - where you can pretty much find gems for so many things out there. (e.g.: tagging, authentication, etc). There simply isn't a comparison.
So, while I really love Clojure and I believe the community around it is growing - in both size and its contributions, I would say that, let's face it, writing full web apps in it right now cannot be compared to the productivity you would get in say RoR, due to the immaturity of the tools.
That being said, I still see Clojure being immensely useful in other scenarios (for example: A.I. algorithms, high performance data processing, etc) and as such I would use it mostly in those settings, while integrating it with a more mature 'front-end' framework.
I had the exact same experience with a project we started recently.
We jumped from Clojure/Compojure to Erlang/WebMachine with much better success so far. I did in Erlang in two days what Clojure took me two weeks with numerous false starts to accomplish, mostly because the libraries were so poorly documented or incomplete. I spent more time digging through code and trying to assemble a framework to build upon than I did writing useful business logic.
I found the Erlang infrastructure to be well-structured and strongly documented, mostly because of it's maturity. What I surmise is that Clojure is just too young, and its web framework lacks a strong commercial force driving it. Rails has 37signals, Webmachine has Basho, Lift has sites like Twitter and Foursquare. Clojure needs something similar to push it forward.
All arguments and emotions aside, I'd say if you're starting to build a new web site, and you're not considering Rails or Lift, you're doing yourself a major disservice. Like others have said, JRuby nicely avoids some of the issues discussed for scripting languages.
I managed to use Apache Velocity with clojure reasonably easy. Maybe not the sexiest template engine around, but it's what I was used to. Plus I can just plug a clojure bit in the existing java webapp and not have to change anything else.
Lack of docs is to be expected, it's early days. That may be a turn-off for some people. On the other hand, it's a great time to get your own preferred features and changes added.
As far as I know, nothing is stopping you from using any of the existing templating systems in the Java ecosystem. They don't have to be written in Clojure to use them with Clojure.
But even if you go through the initial pains of figuring out how things fit together, many tools are still missing. An easy to use templating library, for example. (several exist already but they are still early stages /are being refactored). Also things like the gems and plugins ecosystem in RoR - where you can pretty much find gems for so many things out there. (e.g.: tagging, authentication, etc). There simply isn't a comparison.
So, while I really love Clojure and I believe the community around it is growing - in both size and its contributions, I would say that, let's face it, writing full web apps in it right now cannot be compared to the productivity you would get in say RoR, due to the immaturity of the tools. That being said, I still see Clojure being immensely useful in other scenarios (for example: A.I. algorithms, high performance data processing, etc) and as such I would use it mostly in those settings, while integrating it with a more mature 'front-end' framework.