Feature and Review branches are a great idea. It just makes it so easy to work in parallel on different things, and to context-switch when you get blocked. Honestly, I can't remember how we used to solve these problems with SVN. If you're in the middle of developing a feature and need to wait for someone to get back to you, the options for switching to a different feature with SVN are pretty limited.
This is interesting. What I'm curious about though, is how does this workflow scale to thirty developers? 100?
I tend to believe with six people or less, you can really work together with any system and it will work fine. Some will obviously require more work than others, but once you get to a larger team, some systems just won't work, AFAIK.
From my experience with working with 50+ developers, organized into teams of 3-8 people:
Feature branches are the way to go. We used an adapted version of the git-flow workflow and it does scale pretty nicely.