After 16 months of waiting, Apple's (sort of) next generation iPhone went on sale this Friday. After the disappointment following Apple's keynote on the 4th, we were all wondering how the 4S would really stack up. On the outside, the iPhone 4S looks almost identical to its predecessor. And despite the addition of an A5 processor and 8-megapixel advanced lens camera, this is the first time Apple has really had to stress software over hardware.

So how does the iPhone 4S compare to the competition? Is it a worthy upgrade to the iPhone 4? Or is it missing too many key features? After two days with the 4S, here are a few of my findings:

• First things first, the design hasn't really changed a lot. The antenna has the newer design, as seen in the CDMA iPhone, and there is a little more text on the backside. Other than that, it's virtually identical to the iPhone 4: the same bright, high density display, the same glass front and back, and the same buttons and port positions. It still feels great in the hand and the display is still a tad too small.
• One major external change that Apple made, though it looks very similar, is the antenna. Learning from the antennagate debacle last year, Apple redesigned antenna to "intelligently switch between to antennas to transmit and receive, so call quality is better." I haven't really experimented with this yet, and I haven't necessarily had any problems with call or signal quality. But I have experienced intermittent data connectivity issues.

• Although it's no real surprise, one key feature that is missing is 4G. Every other high-end smartphone on the market now ships with 4G. It's worth noting that the clocked HSDPA speeds of the 4S have been roughly comparable to other HSPA+ phones on AT&T, but we all know that's not really 4G. Unsurprisingly, data speeds have been on par with my CDMA iPhone 4. But as I stated before, I have had more issues with data connectivity. More on that in the full review.
• One of the two major changes featured on the inside of the device is the processor, which has been bumped to an A5 dual-core processor. That is the same processor featured in the iPad 2, although they're clocked differently – the A5 in the 4S is clocked at 800MHz. Quite honestly, unless you're a die-hard mobile gamer, the dual-core processor isn't necessary. The A4 in the iPhone 4 was plenty fast for day to day tasks.
• I'm not going to focus a lot on battery life in this impressions article, as I have some doubts about what is going on. But thus far, battery life has been less than stellar, to say the least. Standby time has been spectacular, but in use, the battery has drained roughly twice as fast as the iPhone 4. I've tweaked everything I know to tweak and am moving on to calibration tonight. I'm not sure if the A5 is the culprit or if the battery just needs a little time to stretch and adjust, so I plan on doing more extensive testing before I definitively say something is going on with the battery.

• One of Apple's biggest gambits with the iPhone 4S is Siri. So far, Siri and I don't exactly see eye-to-eye. It's a great feature and can be very useful. Dictation mode during text input is extremely accurate and it does a pretty good job of answering most of my questions questions. But I can't honestly see myself using Siri in a serious way. It's more fun to ask ridiculous questions (see above) than to look up local restaurants or to ask for the weather.
• Last and certainly not least is the camera. Apple bumped it to 8-megapixels and added "five precision elements to shape incoming light, which makes the entire image sharper." As you probably know by now, this is the sole feature I've been looking forward to in the iPhone 4S. I've been snapping pictures like they're going out of style, and some have quite literally blown me away. Low-light shots are fantastic; there is some noise worth noting in some of the shots I've taken, but colors look very natural. As for natural lighting or even bright settings, the 4S' camera does a great job of not over exposing, maintaining clarity and produces very accurate colors. Microsoft has some stiff competition if they want to offer the "best camera you will ever own."

Keep it locked on PhoneDog for more iPhone 4S coverage and my full review later this week!