When semitethered JailBreak came out, it had many issues which needs to be resolved. Even the creater had no idea about the issues you could face with different devices other than iPhone 4 GSM. Now, the things have started becoming more clear than they were previously. Also, semitethered JailBreak has been updated to version 0.7.9 which fixes several issues.
BigBoss has concluded that he had fixed most of the problems which you could have experienced after installing semitethered package. One of them includes the inability of the device to sync with iTunes, rebooting of the device after 2-3 minutes and an App Sync issue which is impossible to be resolved. According to BigBoss, Appsync doesn’t use mobile substrate. Instead, it hard patches some of the files due to which it can’t work with semi-tethered JailBreak.
Some of the other issues which people are facing would be fixed after the mobile substrate update from Saurik. This update would be out in two or three days. All you need to be patient till it hits the update section of Cydia. Therefore, semitethered JailBreak would ultimately come out of the beta, making it the most usable tethered JailBreak ever. This update would also address an issue of 90 seconds respring on boot.
However, the update has only been tested on iPhone 4. As soon as Saurik releases the mobile substrate update, other device will be tested for sure. Stay tuned for more!