Correction: An earlier version of this article said the iPhone 4S came in 8GB, 16GB and 64GB models. However, there is no 8GB model. This version has been corrected.

Apple released its new iPhone, the 4S, on Tuesday. The new handset has a faster processor, better camera and deep voice integration and is available on Verizon, AT&T and Sprint.

There’s always a collective cry that rises whenever Apple release a new iPhone: “Should I upgrade?” It’s particularly difficult when, as is the case with the 4S, a phone gets half of a makeover. For the faithful who held on to their iPhone 3GS handsets and want to upgrade, it’s an easy choice to make. Customers with the iPhone 4, however, will have to decide if the Siri voice assistant and upgrades to the camera, HD video recording and processing boost are enough to (probably) break contract and shell out the full price for the phone.

For new customers — or those looking to switch carriers — here’s a quick guide to the iPhone on each carrier.

Sprint: The newest kid on the iPhone block, Sprint’s main appeal for iPhone users can be summed up in two words: unlimited data.

The company is currently the only nationwide carrier with a fully unlimited data plan with no caps, no throttling and no overage charges on data.

The average customer can get an unlimited data plan on the iPhone from Sprint starting from $79.99 per month when you add up its 450 minute Everything Data plan and $10 per month smartphone fee. A 16GB model will set you back $199.99, a 32GB model will cost $299.99 and the new 64GB model will be $399.99.

Sprint is also getting its hands on the iPhone 4’s 8GB model for $99.99 on contract, which is also eligible for unlimited data plans.

Verizon: Verizon returns with its second go-round of iPhone sales, offering a bit more variety than Sprint. While the pricing is the same as Sprint’s for the 4S and 8GB iPhone 4, Verizon also has the 16GB and 32GB flavors of Apple’s previous phone. And they’ve dropped the price on those models; you can get the phones for $149.99 and $199.99, respectively.

Picking up an iPhone on Verizon requires at least a $39.99, 450 minute talk plan and $30 data plan.

Verizon’s strongest asset, however, is its network. Several head-to-head tests between the Verizon and AT&T iPhone have shown that Verizon users have fewer dropped calls.

AT&T: AT&T’s strongest asset on the iPhone is that its GSM network gives users the ability to surf and talk on the phone at the same time, which comes in handy in a number of situations. The iPhone 4S requires a data plan, which, on AT&T, starts at $15 per month for 200MB and goes up to $125 for 12GB per month.

AT&T’s also making it easy on its those who want to upgrade, offering an app that lets you check your eligibility and preorder a new phone straight from the iPhone that’s in your pocket right now.

Being the original iPhone carrier has its perks as well, and AT&T hasn’t been shy about touting the fact that it has the most models of the iPhone to offer. In addition to carrying all the 4S and 4 models at the same prices as its competitors, AT&T is also offering the free-on-contract, 8GB iPhone 3GS.