Yes, it's perfectly fine to install. It was turned into a real patch for everyone to get...you can download and install it now. It's unofficial, and the install is a little different then most people are used to, but it really does improve the game. It's sort of just something to tide us over until the next official patch is released. I think once people realize that the patch is out there, and they just slowly follow the directions on installing, everything will be all good. It makes a totally new directory, so if you launch 1.1e/f - youll see servers with the 1.1 patch. If you want to see 1.0 servers, you'll have to launch 1.0. I can tell you already though, the same servers will be in 1.1 that are in 1.0...and with more slots and gameplay modes. =)
I think it's a good idea to upgrade...as you'll still be able to play on the 1.0 servers anyways.