Source: http://lifehacker.com/5741627/why-you-might-want-to-wait-for-a-4g-phone
If you're getting pretty excited about all the new speedy, 4G phones coming out right now, you're probably thinking of picking one up. Tech blog Tested reminds us that it's still a new technology, and you may be better off waiting.
We've already addressed the differences between 4G on each carrier, but 4G has a lot of general advantages and disadvantages over the standard 3G phones most of us are still rocking. Of course we all know the advantage: blindingly fast speed. But that isn't the whole story.
At the top of 4G's list of disadvantages is bad battery life. As with 3G, mobile data is a bit of a battery suck, and 4G is going to be a worse offender than 3G. Battery life is already a pretty big problem on a lot of today's smartphones, so if you think you're going to find yourself toggling 4G off just to make it through your day, it may not be worth springing for a whole new phone right now. Furthermore, to combat this, many phones will have larger batteries, making the phones bigger and heavier (but likely still having less than stellar battery life). And, while you can get some pretty blindingly fast speed on 4G right now, as more people pick it up, your average speed will decline a bit. It will, of course, be faster than 3G, just not as much faster as you might think right now—meaning that switch might not be as worth it as you think.
Check out the article at Tested for even more reasons you might want to wait, including some interesting info on voice standards and frequencies. Of course, this doesn't mean you shouldn't spring for a new 4G phone—particularly if your current phone is older than dirt—but the much more realistic view on the technology is welcome for those of us making phone buying decisions.