What kind of skill sets does your team have? If you are new to Java and/or J2EE then you will struggle with Nukes. The code is not yet to the point where non-programmers could set up a site and customize it to their liking.
I've been using Nukes for about 3 weeks and I have a site already up and running, but I have a team of people with strong Java skills. I had to write a lot of custom code and I had to hack quite a bit of the Nukes source code to customize things they way we needed them. Overall we are extremely happy with how things have worked out and how quickly we could put a web front-end on our pre-existing Jboss server.
- Cool security model that makes role-based permissions easy
- Template system that lets you keep html code in html files and java code in java files
- Handles transactions which eliminates the need for Session EJBs
- JMX - this is awesome and you will only get this with Java. Lets you hot-deploy modules, make inter-module method calls using reflection, configure security w/o recompiling source code, etc.
- A Forum that, desipite its quirks, works pretty damn well.
- Scalability - Should scale as large as you can imagine
- Get ready to hack source!
- No documentation. The tutorials are nice for giving you an overview of how stuff works, but it is impossible to get a site up and running from scratch only reading the official content. If you can't follow the source code and understand what is going on you will be totally lost.
- Community is still pretty small, so there are not many modules
- SSL is not really built into the design. More specifically, nukes can support SSL, but it is not really set up in a way that makes it easy to have part of the site on https and other parts on http. Maybe there is a way but I have not yet figured out a good plan.
- Look & Feel is not 100% customizable. Blocks and Modules still have quite a bit of hardcoded HTML
- User Module (registration, etc) is not customizable at all without hacking source. We wrote our own version of the UserModule so that we could capture extra fields and change the login flow to match our needs.
Again, I am still pretty new to Nukes so take my comments with a grain of salt. Overall I think Nukes is great and I think it is going to get even better as it grows.