My iPhone 3Gs suffered some of these reported problems - screen freezing and poor battery life were the main problems. The screen freeze was an immediate problem from receipt of my new phone (3 weeks before 3.1 came out). This was replaced by Apple after having to run the phone with no 3rd party apps for about 8 hours to convince them it was not due to a dodgy app.
Then my battery life went to about 1% usage every 2 minutes after the 3.1 install. After reading the Apple discussion boards one user said it was due to the battery management software being upset by 3.1. The solution was to ensure you have a current iPhone backup (via iTunes), then reset and restore from your backup. This solved the problem, in fact my battery seems to last longer than pre 3.1.
This is just one of many "tech" issues I have had to deal with since buying an iPhone almost 2 years ago.
I would add that you need to be reasonably computer literate to deal with all the possible pitfalls of owning one of these devices. At £538, it is not far off the price of a Macbook and certainly more than the raft of elCheapo laptops on the market. This is a clue its not really a phone, but a very sophisticated mobile computing tool.
I am sure the smart people at the Genius Bar could sort many of these problems for an inexperienced user (but then you may need to lug your computer in with you to get the full service which is not really practical). But most of us in the UK have to travel a long way for that help.
I would advise everyone who doesn't think they can manage the high tech curve for using an iPhone to either wait for quite a while longer for the product to mature. But if you have one or really want one, then stump up the £59 for the Apple Care plan. This will ensure they will stay on the phone with you until you get it sorted at no cost to you (other than the £59 of course). This includes shipping another phone to you (before you return a duff one to them) at no cost, which is essential if you use the iPhone as a business tool or cant let your Farmville crops go untended for even an hour.
With the exclusivity deal coming to and end for O2 shortly, the increased uptake of the iPhone may depend on the support provided by the mobile phone operators selling the iPhone. O2 may really struggle with this as some of the sales staff cant evendeal with simple instore stock systems. Who knows how the Orange / T mobile marriage will fare.
Our lives are becoming very IT / gadget entangled. Even todays TV / HD recorder combos sometimes require significant gadget savvy to use.
Perhaps we are entering an era where the "gadget geek" may well become as integral to society as shamans of the past. Perhaps as distrusted too. I wonder what the peasants will be offering up as sacrifices in 2109.