@Hell_Diguner, I consider the current version in a sort of early-middle phase. The core functionality is complete with the portals and a basic nether surface operational. I'm happy with where it's at, but going forward I do want to add a lot more cosmetic stuff to make it pretty like particles for the portal, lava lakes in the nether, custom achievements, potentially even some nether biomes with their own trees, decoratives, tiles, etc. Much farther down the priority list would be stuff like nether mobs (probably won't happen for a very long time). That being said development has been quite slow as I now have a full-time job and just work on mods when I have some free time. I wouldn't count on any big changes to the mod soon, though I am still working on it and want to make it better.
If you've got any ideas/suggestions (or want to help with development) let me know! The more interest people show the more motivation I have to work on it :D