The hardware design is, as far as I can say, final. We have three boards atm and will be making three more soon. What we're working on is the software. People will expect something usable, stable. You would not want lockups here and there, data loss, or a board not working in your Amiga because it's got some fix applied or not.
When we (actually Herzi, "NewAmigaUser" on a1k.org) started, the idea was "let's make an accelerator". It became a "one device does it all"-thing. It gives you ram, it gives you roms (switches between whatever Kickstarts you have and flash into it). It gives you a NMI-button, acts as a Action Replay 3 (with blessing from the original authors btw), supports WHDLoad and the exit button, adds an HDD controller (Gayle IDE or AT-Bus 2008 if you have the rom) and it fits right into your machine so you can carry it around. There's nothing to add to your expansion port, no worries about an enclosure. Depending on the machine you want to use it in, you might have to relocate a capacitor, and the A1000 and the CDTV need an adapter cable. But these things really aren't an issue looking at what people modify to get the Amiga they dream of.
There even is a config tool on the Amiga side (CLI and GUI) which you can use to manage the system and roms once you have installed it in your computer.
The source for the FPGA will allow you to add more features and tinker with it. If you're a power user and you "break" it, connect the JTAG and revive it.
There's really loads of stuff in it, and you hopefully don't need any other device to get the functionality you are looking for. I think it's in a state where it could be sold already, but we still want to add things to release a package that is out of beta.
So, to come back to your question... it became much more than we initially planned. These things take time to do them properly. I am confident that this device will be in the hands of users in 2013.