It’s a beta release, intended for bona fide developers to use to test out their apps on the new iOS version prior to it being released to the general public. If you are not a developer (or working for/with one to test their apps), DO NOT GO THERE.
yes frnd you can update it ... but after update ios7 ur i4 will get work very slow as it developer version.
ios7 install and work perfectly its imaging future as well but just work slow on every step ,
i already tried it on it no issue and now i got roll back to ios 6.1.3