Yesterday we reviewed why the iPhone 4s is a worthy update to the iPhone 4. Today we offer an alternative view and discuss why the iPhone 4s might not be worth an upgrade for some users.

As Apple’s iPhone event wound down yesterday, many people were hoping Tim Cook would pull out Steve Jobs famous line, “One more thing,” and introduce the iPhone 5 that so many of us were anticipating.

That line never came, and we were left with the iPhone 4S as the new Apple phone. Some people were fine with the announcement, but others, who had been waiting for a new form factor and a bigger screen, were left disappointed. As soon as that iPhone 4S flashed on the screen in Cupertino, Apple stock dropped 2%. Twitter exploded with tweets from angry Apple fans, and message board entries displayed the dissatisfaction of receiving an iPhone 4S instead of an iPhone 5.

The iPhone 4S is a significant upgrade to the iPhone 4, just as the 3GS was a much faster version of the 3G. But here’s the problem: The iPhone 4 design is 16 months old. It’s stale. It’s boring. We’re used to Apple giving us faster, thinner, sleeker devices on a regular basis. Every other iPhone release was in the month of June or July, with an update coming every year.

The iPhone 4S marks the first fall release, and it was a reasonable assumption that since an upgrade took 16 months instead of 12, something big was coming. And Apple scheduled a big event. The iPhone 4S announcement plus the news that the iPod Touch now comes in white was not big at all. People would be less disappointed if Apple hadn’t made such a hubbub about an incremental upgrade.

Beside the iPhone 4, the iPhone 4S is a decent upgrade. It features an improved camera, an A5 dual-core processor, dual-core graphics, and faster downloading speeds.   But beside other top of the line Android phones (Samsung Galaxy S II, Motorola Droid Bionic, HTC Titan), the iPhone 4S is nearly outdated.

Those phones all have faster processors and more memory. The Galaxy S II beats or equals the iPhone 4S in almost every category, from display technology and display size to battery and weight. The only thing the iPhone 4S stands out for is its significant internal storage, display resolution, and media playback time, but it really falls behind on processing speed, memory, and display size. The iPhone 4 is 3.5 inches, while other top of the line phones from Apple’s competitors all feature 4”+ screens.

Where’s the innovation? Where’s the blow-your-mind designs that Apple is famous for? The designs that every other manufacturer tries to emulate? This is a barely competitive phone that looks exactly like a phone that we’ve been using for 16 months. It’s hardly worth an upgrade.

My iPhone 4 works fine. It’s sufficiently speedy, the camera is fine for Twitter pictures, and while Siri is cool, I’m not enthralled with the idea of speaking to my phone. The iPhone 4S might be moderately faster, but it doesn’t entice me to buy the iPhone 4S at this point.

If you have an iPhone 3GS or earlier model, then the 4S is definitely a huge upgrade that’s worth a new contract. Go for it, get the iPhone 4S and revel in the amazing speed increase and retina graphics. Likewise, if you’re a Sprint customer, you will be awed by the splendor of an iPhone. It’s a must have, especially compared to the other lackluster phones that Sprint offers.

If you have an iPhone 4, this is an upgrade you should probably skip. The iPhone 4S is faster, but the screen size and resolution are the same. With iOS 5, you’re getting the same software, and the touted network speed advantage is only a minor increase that’s not 4G. The only feature you won’t have access to is Apple’s new built-in personal assistant, Siri.

The iPhone 4 will last at least another year, and a mid-season upgrade will lock you into a new contract, making you ineligible for an upgrade during a summer or fall 2012 iPhone 5 release. Many of you who purchased an iPhone 4 at release, like I did, will soon be eligible for an upgrade. But purchasing an iPhone 4S within the next few months will mean you’re not eligible for another phone until April of 2013 or even later (at least, with carriers in the U.S.). And that means no shiny new iPhone 5 for you when it comes out, unless you’re willing to pay the non-subsidized price, which is pretty hefty.

I won’t be upgrading. The iPhone 4S doesn’t have enough to offer, so I’m going to hold out and hope that Apple bounces back and releases a phone that’s truly innovative rather than a rehash of an old product.

Are you going to upgrade to the 4S, or stick with your current phone? What’s your reasoning? Let us know in the comments.