To buy or not to buy, that is the question.

Countless iPhone and other smartphone users — myself included — have been waiting for years for this week to arrive. Verizon, which operates the nation's largest wireless network, is finally offering its version of the vaunted iPhone. But, now that the time has come, is it the right move?

Many factors weigh in on a purchase like this, so for many people getting a Verizon iPhone4 may make sense. Maybe it's an upgrade from a non-Apple device or a pent-up need to move away from AT&T's sometimes sketchy wireless service. But the way I see it, now is not the time to make the jump — at least not for me.

Why? Well, there are two main reasons:

First, the next generation iPhone may coming sooner than you think. Why get locked into an iPhone4 when all signs are pointing to the launch of a brand new (and most likely very snazzy) iPhone5 this summer? Let's face it, although the iPhone4 is new to Verizon, it is, alas, last year's model. And although Apple isn't saying when it will launch its next generation handset, the smart money is betting it will happen this June or July, which would follow the pattern of the last four years when Apple released a new iPhone each summer. 

Other factors suggesting a fairly imminent launch include tips from anonymous sources that have provided very accurate intelligence about Apple products in the past; deft analyses of Apple orders of chipsets and other components for a new device; and quite probably some form of tech-geek divination involving old iPhone parts, a lock of Steve Jobs' hair and a Jedi training manual.  Nonetheless, the conventional wisdom is that the newest version of the iPhone will very likely come out very soon.

And it's worth the wait because the next generation iPhone is expected to run on the next generation network: 4G. You may have seen the ads for 4G service. Chris Ziegler, Senior Mobile Editor for Engadget, said the difference in download speeds between the current 3G networks and 4G will be huge.

"In real-world use, we've seen speeds anywhere from five to about 30 megabits per second on various 4G networks from different carriers versus between about one to three or four megabits per second on 3G networks, depending on your area," Ziegler said.

Everything will run faster on a 4G network — Web surfing, emailing, streaming and especially real-time multiplayer gaming, which Ziegler said is expected to become a big deal in the next few years.

And despite the "4" in its name, the iPhone4 on sale today will not work on the new and faster 4G network.

As we look beyond the horizon for that yet-to-be announced faster 4G iPhone of our dreams, is there decent 4G coverage in the New York City area? Between the two iPhone carriers, Verizon has the leg up. It's already up and running with 4G service in New York and plans to have nationwide coverage by 2013.  AT&T, on the other hand, will start building its 4G network mid-year, with nationwide coverage also expected to be complete by 2013.

The other main reason I'm holding off on an iPhone4 from either Verizon or AT&T right now is network reliability. Although Verizon has come out on top in customer satisfaction surveys, there is no telling what might happen when all those new bandwidth-hungry iPhones start latching on to the Verizon network. Verizon says it's ready for the onslaught, but that's exactly what AT&T said when it first introduced the iPhone four years ago. And we all know how that went.

But Ziegler thinks Verizon will be able to handle the increased volume.  He says he's cautiously optimistic for a couple of reasons.

"First of all, they kind of had a nice warm-up with all the Droids that they've deployed so far, because those are extremely data-intensive as well," he said. "So they've already gotten a taste of what it's like to have their network swamped with high-data users. They have a good sense for what that means. Also, they announced last week that they are reserving the right to throttle extremely heavy data users going forward."

That means if Verizon feels you're using too much data, they'll either start compressing your data or they'll make it slower for you, so the network as a whole doesn't bog down. Ziegler also said it doesn't hurt that Verizon is intensely aware of not doing anything to ruin its good reputation as a stable and reliable network.

Though I'm waiting a few months for a faster 4G iPhone and avoiding some uncertainty about how Verizon will handle all that new traffic, those dead-set on getting an iPhone4 should consider other factors, of course.

If you're in the middle of your service contract, breaking it to switch carriers could cost you hundreds of dollars in early termination fees. The Verizon iPhone won't allow you to talk on the phone and surf the Web at the same time, like AT&T. And, if you plan on using the phone overseas, AT&T's iPhone works in far more countries than Verizon's.

Also, if you're a heavy downloader and don't care about what the summer may or may not bring, Ziegler said you might want to stick with or go for AT&T.

"If you want to talk about raw data speed, AT&T's [3G] network does top out at a higher speed than Verizon's so if you do a lot of downloading with the iPhone and are willing to put up with the occasional dropped call, AT&T's iPhone will technically be faster than Verizon's," he said.

With that all said, and as long as my terribly overburdened 2-1/2-year-old iPhone3G valiantly carries on, I plan on holding off for a few more months to most likely join the next round of iPhone-mania — the one over the all new built-from-the-ground-up iPhone5. 

Who knows? It could come not much later than Memorial Day!

Listen to Soterios Johnson speak with Engadget's Chris Ziegler.