Ruby on Rails or the joy of instant feedback.

I wrote a longer entry on my blog (http://lonelywolfsden.blogspot.com/2010/12/ruby-on-rails-or-beauty-of-instant.html) but as a Java developer I am positively impressed with the possibilities opened by Ruby on Rails.
I was trying to implement a complicated GWT +MAVEN + GAE application for a month and got lost in some configuration details. . so I just left the project in pieces on my SVN folder. A week before I had installed the sample depot application of Rails in Netbeans. Saturday morning I had started to create a new RoR application.
After just 24h I had managed to get something working and using it (personal pet project).
The key features of RoR for me :
1) Scaffolding
2) Instant feedback ( according to http://www.zeroturnaround.com/blog/java-ee-container-redeploy-restart-turnaround-report/ we loose 25% of our time just compiling and deploying ) which I think is crucial these days.
As an ex-PHP programmer I can say that Ruby(on Rails) has the power of Java (and the good software engineering approach) with the instant developer feedback of PHP (interpreted language development).
Would I architect a bank application with Ruby on Rails ? No .. I mean maybe the front end (web layer with JRuby at most).
Would I do anyhing I implemented in PHP before in Ruby ? Of course .. 1000 .times { puts 'yes'}
I am dissapointed that people on Javaranch do not write more on this forum but nevertheless I am happy to be writing here.

Now to ask a question : say I have created a model with a integer value like car.max_speed. How do I change it to float without regenerating the model ? The field in the DB is ok.

I wish if you asked your question immediately...

Mihai, you would refactor it.
Also, I don't that scaffolding is a major feature of ror. Apart from general CRUD pages for a Model, it doesn't do much. So, for any customization, you need to write your own implementation.

Well since I am such a noob .. I figure I might answer this.
All you need to do in these cases is to restart the development server (WebRick). Meanwhile I have managed to get my application going at a pretty good speed and I think that Ruby on Rails is great for small web applications.
Unfortunately I will stick to J2EE for really critical enterprise apps. Things like 2 phase commits and lack of standards deter me from considering RoR for more elaborate enterprise solutions .. for now.
But as I am sure most of you found out too it bring back the joy of programming a bit.