The unlock is actually quite easy, safe and reversible. However if you read all the iPhone forums there are way too many complications, I suspect because people are not researching the issues, reading instructions or the readme and because there are plenty of people who have been unlocking phones since firmware 1.02 with other means and this mix of issues with older phones and the new phones with new unlock methods creates even more complications.
For those who get a brand new 113 firmware phone (to check dial *3001#12345#* in the emergency screen of the new phone and go to the firmware section to check the baseband info, if its show 4.03.. its firmware 113, if it shows 4.04.. its firmware 114.) all it takes is Ziphone 2.3, and the command ziphone -a -u -j (don't use the gui, use the commandline) and 2 and half minutes of your time. Provided this is a brand new untouched 113 phone it will work flawlessly 100% without issues.
If you have firmware 114, you will have to workaround slightly, this because if you use the default options in Ziphone 2.5 which is meant for firmware 114, your bootloader will be downgraded to 3.9 which many newbies are realizing after they have done this irreversible downgrade.
To use Ziphone to unlock firmware 114 without downgrading bootloader you have to use a workaround. First use Ziphone 2.5c (the latest) to jailbreak and activate(ziphone -a -j) and then Ziphone 2.3 to unlock(ziphone -u). Why this mix and Ziphone 2.3? Because Ziphone 2.3 will downgrade your baseband to 4.02, which Ziphone 2.5 doesn't do.
Now the real deal. There is a new solution called iPlus exclusively for firmware 114. The thing is Zibri, author of Ziphone, was part of the dev team (the group who are making the programs that make this unlock possible) and went his own way using their hacks and 'packaging' it for his program and cornering the donations. We don't want to get in the politics of this but iPlus is from someone who works closely with the dev team and donations go to the dev team.
iPlus's USP is that it enables a unlock of the latest basebands ie 4.04 without downgrading your bootloader to 3.9 which Ziphone does. What it does instead is downgrade your bootloader to 3.9FB. Pay attention here folks, notice that FB, that stands for fake blank and its a modified 3.9 bootloader that
CAN BE UPGRADED TO 4.6. The default 3.9 bootloader cannot be upgraded to 4.6 at the moment. So iPlus is the best of both worlds you get the latest matching basebands and a bootloader that can be upgraded back to 4.6 making everyone happy. There is a new version 2 available and people are reporting success.
So for those with new phones with firmware 114 firmware its as simple as downloading iPlus and using it. For those with firmware 113 they can go the Ziphone way with version 2.3 or upgrade firmware to 114 through iTunes and go the iPlus way. Whatever you do don't downgrade your bootloader.
eziphone.blogspot.com - all versions of Ziphone
The Sweet Spot for iPhone's iPlus - iPlus home
[1.1.4] iPlus 2.0 - Unlock/Downgrade, jailbread, activate and more! - Hackint0sh - iPlus thread and links
iclarified.com - excellent tutorials for all firmwares
hackthatphone.com - same as above
hackint0sh.org - iPhone community with solutions to all problems