Apple Stores, resellers, and carriers in the United States, Australia, Canada, France, Germany, Japan and the United Kingdom are opening their doors today, Oct. 14, to people eager to be the first to get their hands on iPhone 4S.

While it doesn't have any design changes from its predecessor, iPhone 4S has an upgraded processor, camera, software, and features as virtual assistant. The release of iPhone 4S, which, was the last new Apple device in production before Apple's founder, Steve Jobs, died, will again be subject to long queues and camp-outs outside Apple stores.

iPhone 4S comes in either black or white and will be available in the U.S. for a suggested retail price of $199 (US) for the 16GB model and $299 (US) for the 32GB model and $399 (US) for the new 64GB model, on a standard two-year contract.

iPhone 4S will be available from the Apple Online Store, Apple's retail stores, carriers or networks, and select authorized resellers, which include including Best Buy Co. Inc. and Wal-Mart Stores Inc.

In the U.S., the new iPhone will be available in major carriers AT&T, Sprint, and Verizon Wireless. Carriers have started accepting pre-orders Oct. 7.

iPhone 4S will be available at all 245 Apple retail stores in the U.S. beginning at 8 a.m. local time on Friday, Oct. 14.

Apple Stores have also accepted in-store reservations but many more are lining up for on-the-spot purchases.

Those who hate the long two-year contracts -- and the termination fees when opting out -- can purchase unlocked versions of iPhone 4S. The 16 GB model is priced at $649, the 32 GB is at $749 and the 64 GB is priced at $849. The unlocked iPhone 4S works only on supported GSM networks, such as AT&T in the U.S. When you travel outside the U.S., you can use a micro-SIM card from a local GSM carrier.

Android and BlackBerry users who want to switch to Apple but finds iPhone 4S expensive can try out the iPhone 4, which was unveiled June last year. The price for the iPhone 4 has been slashed to $99 on a two-year contract.

iPhone 4S will roll out worldwide to 22 more countries by the end of October including Austria, Belgium, Czech Republic, Denmark, Estonia, Finland, Hungary, Ireland, Italy, Latvia, Liechtenstein, Lithuania, Luxembourg, Mexico, Netherlands, Norway, Singapore, Slovakia, Slovenia, Spain, Sweden and Switzerland.

10. Siri. iPhone 4S has a built-in digital assistant, called Siri. "What we really want to do is talk to our device. Siri is your intelligent assistant and helps you get things done, just by asking," says Phil Schiller, Apple's marketing chief. While the iPhone 4 and the iPad can be upgraded for FREE to iOS 5, Siri is exclusive to iPhone 4S. While Android phones have improved in specs and screen sized, their voice-recognition systems can't beat Siri.

9. Apps. Apple announced pre-orders of its iPhone 4S have topped one million in a single day, surpassing the previous single day pre-order record of 600,000 held by iPhone 4. More apps means that more third-party developers would be creating better apps for iPhone 4S. You'll have more apps that are secure, malware free and optimized for iPhone 4S.

8. Storage. iPhone 4S has 16 GB to 64 GB of built-in storage, which is not really superior to the Samsung Galaxy S2 or the Nexus Prime. But there's iCloud, which has 5 GB of free cloud storage for Mail, Document Storage and Backup. Purchased music, TV shows, apps, books and Photo Stream do not count against the storage limit. Additional iCloud storage upgrades are available to purchase starting at $20 a year for 10GB, $40 a year for 20GB and $100 a year for 50GB.

7. iCloud. The sky's the limit when downloading and managing content on iPhone 4S because of iCloud. iCloud stores your music, photos, apps, contacts, calendars, documents and more, keeping them up to date across all your devices. "iCloud is the easiest way to manage your content, because iCloud does it all for you and goes far beyond anything available today," said Eddy Cue, Apple's senior vice president of Internet Software and Services. "You don't have to think about syncing your devices, because it happens automatically, and it is free."

6. Camera. The brilliant minds at Apple have placed inside iPhone 4S an all new camera with the most advanced optics of any phone. The camera can shoot 8-MP stills (3264 by 2448 pixels) and recording 1080p videos at thirty frames per second with better clarity, better white balance, and color accuracy. iPhone 4S includes a new custom lens, a larger f/2.4 aperture and an advanced hybrid IR filter that produce sharper, brighter and more accurate images. The Apple-designed image signal processor in the A5 dual-core chip is built for performance, and coupled with the features built into iOS 5, makes the camera one of the fastest on any phone. With iPhone 4S, the Camera app launches much faster and the shot to shot capability is twice as fast, so you'll never miss another shot.

5. iOS 5. When Apple says it has the most advanced operating system, its assurances are usually fool-proof. For iPhone 4S, the many surprises in store for Apple fans is in the inside -- iOS 5 includes over 200 new features including Notification Center, an innovative way to easily view and manage notifications in one place without interruption and iMessage, a new messaging service that lets you easily send text messages, photos and videos between all iOS 5 users. Though iOS 5 is already available as a free software update for iPhone 4, iPhone 3GS, iPod touch third and fourth generation, iPad and iPad 2, this new software update works best for iPhone 4S. People updating these devices are receiving error messages -- Error 3200 and 3004 -- which is not really a compatibility problem, but an issue of massive amount of simultaneous downloads for the new software.

4. Processor. Two cores in the A5 chip deliver up to two times more power and up to seven times faster graphics. iPhone 4S is quick and responsive, which makes all the difference when you're launching apps, browsing the web, gaming, and doing just about everything.

3. Aesthetics. Yes, the 3.5-inch screen could be bigger, something like the Galaxy S2's 4.3-inch Super AMOLED Plus display.

But there was nothing wrong with the aesthetics of the iPhone 4. As PR guys from Apple claims, iPhone 4S has the same beautifully thin glass and stainless steel design that millions of customers around the world love, while being completely redesigned on the inside. What's more, iPhone 4S is already available in black and white (unlike before where the white version came in 10 months late). One thing Jobs most likely imparted on his Apple engineers was to focus on industrial design and aesthetics. But waiting another 4 to 12 months for iPhone 5 is not worth the wait when there's iPhone 4S.

2. Battery Life. Because the A5 chip is so power-efficient, iPhone 4S has outstanding battery life. It offers 200 hours standby time (iPhone 4 300 hours), 8 hours talk time on 3G (iPhone 4 7 hours), 14 hours talk time on 2G, 6 hours 3G browsing, and 9 hours Wi-Fi browsing. The Galaxy S2's 1650 mAh Li-ion battery is enough for 10 hours of heavy usage. But noting of Apple's efficiency and its dislike of battery draining stuff like Adobe Flash, iPhone 4S could last longer.

1. Dual Antenna. Improving on the innovative stainless steel external, dual-antenna design of iPhone 4, iPhone 4S is the first phone to intelligently switch between two antennas to send and receive. iPhone 4S now supports twice the download speed with HSDPA of up to 14.4 Mbps and iPhone 4S is a world phone, so both CDMA and GSM customers can now roam internationally on GSM networks. When traveling outside your country, you can actually buy a micro-SIM card from a local network to avoid the roaming charges and whatever fees. An iPhone that you could tout on your trip around the world? Wow.