I got a couple of things wrong in the previous article. The idea it was only for the SL grid was not right. This release has a version for the OpenSim grids. You can see the highlights of that release on the announcement page: Firestorm Major Upgrade.
Another point on the announcement page is information about the effort that has been put into providing an upgrade path for Phoenix users.
This video runs a little less than 8 minutes.
The video warns that you will have a slow start because they have flushed all the caches.
They also tell you this is not a perfect copy of Phoenix. There are significant differences. There were limits to what they could do with the underlying V3 code.
Firestorm has many more features than Phoenix did. I think these are great features. I also think learning them will make your SL experience much nicer. The video gives you the quick how to on using them. But, if your mind is closed and you want as close a V1 user interface as possible, well… try Singularity.
I personally would not spend developer time on duplicating the V1 user interface. I would let Singularity and Cool VL viewers build the V1 user interface style viewers. There are features that Phoenix had that we have waited on for over a year to be added to Firestorm. I think Firestorm would be better off with those than with the V1 user interface. It is just going to continue to be a sinkhole for effort and time. The more time that passes the fewer people will use it. So, if you like your Phoenix interface, be glad I’m not in charge.