IMHO average user does not use their device to its full potential so in all honesty, not much. However for those who want to actually use the hardware they paid for it matters a bunch.
Our smartphones are nice little computers, and like any tech, they can be used to their potential or not. It just depends who's driving and if they choose to use it.
Personally, I'll mod any tech I find. Much like we mod vehicles.
I hate vehicle/computer analogy's, but sometimes the metaphor works.
The VX can take you to the Dollar General store to pick up cat litter, and if that's all you want, that's fine.
It can also climb rocks, mire through mud, ford streams, kick sand, turn heads and scream down the Interstate. Its just a matter of using what it has natively and adding on or removing as you see fit.
If you want to make phone calls and send text messages, get a pay-as-you-go feature phone from walmart. If you want a smart phone as the original poster requested then I'll stand by my recommendations.
The Experia is a great device hardware wise, but it didn't appear on my list since its firmware is already obsolete and Sony developers do not seem too keen on updating their devices in a timely manner, thus it stays on the back burner.
Root the device, try a few custom roms and report back! I encourage you, mod it!