As many of you guys know, Apple gave us a preview of the next iPhone OS on April 8th 2010. Since then, Apple has released 3 Betas for developers to test out. I was lucky enough to get a legal copy from a developer and have been testing this OS for four days. In the four days, I’ve been loving iPhone OS 4.0 so much, I won’t jailbreak my iPhone again. So, here’s my review:

New Features

Apple says that this new version of the iPhone OS has 100+ features. But, I’m going to cover the major ones.

1. The first major new feature is multitasking. Everyone, including me, wanted multitasking since OS 2.0 and finally, Apple delivered it. To activate multitasking, double press the home button 2 times and a list of open apps will slide up. The way how Apple implement multitasking is excellent and it preserves battery life. In order for them to preserve battery, the applications do not actually run in the background continuously. Instead, it actually pauses the app in the background. Now in the SDK, there are 7 multitasking services like Background VoIP for Skype, Background audio for Pandora, etc. There’s also another neat feature inside the multitasking window. If you swipe to the left, you will get iPod controls and an orientation lock.  The orientation lock is only on portrait for some odd reason. Overall, multitasking is excellent on OS4.

2. The second major new feature is home screen wallpapers, a jailbreak favorite. Before iPhone OS 4, you were stuck with a black background and a plain looking dock. Now in OS 4, you can have backgrounds in the home screen and has an improved dock with reflections. Also, it seems like Apple has tweaked some of the icons. The most noticeable change is the Calculator icon, which looks a lot cleaner and nicer.

3. The third major new feature is a unified mailbox. Back in 3.0 or below, this was a major complaint that I had in the Mail app, but Apple fixed it with the iPhone OS 4. Looking that the picture, you see my Gmail and Tech Cores accounts and right above it is “All Inboxes”. I did not open that for a number of reasons, but trust me, it has both my Tech Cores and Gmail inboxes in one screen.

4. The fourth major feature is folders, which is another jailbreak favorite. Folders in the iPhone OS is simple, yet elegant. If you want to create a folder, press down on one icon, simply drag an icon over another, and bam, a folder has been created. The folders system has an intelligent auto-name system. For example, if I drag App Box Pro and Free Memory, it will auto-name it to Utilities. If you use folders, you can have 2,160 apps, which is a lot.

5. (iPhone Only) The fifth major feature is 5x digital zoom in the camera app. Zoom on the iPhone is a great feature, but zooming too much can make the pictures pixelated and ugly. To activate zooming, touch the screen and a slider would pop up. Once the slider is popped up, you can drag the slider from right to left, or press the + or – signs to zoom.

Performance

Since I have the iPhone 3GS, performance with OS 3.1.3 was great. In OS 4, I’ve noticed a slight performance bump. Boot up/ Shut down is quicker, transitions are buttery smooth, loading web pages and launching apps are quicker.

Conclusion

Overall, I think the iPhone OS is back in the game because of these new features. Are there any complaints? For me, yes, but it’s only one thing. That thing is a better way to handle notifications.  Some times, a blue window popping up in a middle of a video can get really annoying or what ever you are doing with the phone. iPhone OS 4 will be released in the summer and will be compatible with the iPod touch 3rd generation 32/64GB or the iPhone 3GS 16/32GB. OS4 will still be compatible with the iPod touch 2nd generation 8/16GB, and the iPhone 3G, but they will not have multitasking due to the hardware.