The 4S is not substantially more expensive than the 4. Get the 4S. I have a 4 which I use as a backup for my other SIM since I travel internationally a lot. Hate using it. It's laggy compared to my 5 (or 4S) and apps run much slower. If you're looking to use this phone for another 2-3 years, the 4S is a fine choice. Not so sure about the 4.
And I disagree that software updates aren't important. I think they're very important on iPhones because the majority of people upgrade. If an update isn't available to the iPhone 4 in a year or two, you'll be missing out on features that a lot of other people may use. SOCIAL features, in particular. For instance, many of my friends share photostream albums with me. It's an awesome way to share pictures, but it requires iOS 6. People who haven't upgraded simply cannot participate. Now I can't see Apple cutting off OS updates for iPhone 4 until maybe 3 years down the road, but just something to consider.
And I disagree that software updates aren't important. I think they're very important on iPhones because the majority of people upgrade. If an update isn't available to the iPhone 4 in a year or two, you'll be missing out on features that a lot of other people may use. SOCIAL features, in particular. For instance, many of my friends share photostream albums with me. It's an awesome way to share pictures, but it requires iOS 6. People who haven't upgraded simply cannot participate. Now I can't see Apple cutting off OS updates for iPhone 4 until maybe 3 years down the road, but just something to consider.