Yeah...something I'll definitely be inquiring about before I get it....if I get it
I have the unlimited ...they don't offer it anymore....if you have it the upgrade fee refers to you phone only the only thing related to service in that respect is a contract extension ( literally a new phone contract) but you can keep any service you had previously as if they didn't honor previous arrangements it could lead to fraudulent promotional periods that get you in and change on you but still hold you contractually obligated. Make sure you let them know that you wan't to keep your unlimited data transfer plan if you do decide to upgrade.
I still have every iPhone I ever bought (minus the stolen ones) and I can say hands down without a doubt the best one is the first release of the Iphone 3g 8 or 16 gig It has been the most stable longest running device out of all 10+ I have had.
There is countless constituents of choosing whether to upgrade or not.
Based on your location I would guess you have plenty of redundant cell towers in your area but if your left-handed just forget it (I'm left handed and I find myself when people ask about the iphone telling them It's great for everything except phone calls) This isn't a web buzz, this is real, I have more calls dropped than a juggler with no hands.
I think they have fixed the false signal results I used to get but now side by side the iP3g gets two more bars than iP4. Also If your a jailbreaker you should stick with the original 3g or 3gs ( and not use iTUNES to upgrade you FW and baseband )
I use
this (and have only tried it with the iPhone and a friends has tried it on BB) with iP3g and get 1.3-1.5 Mb/s downloads over all protocols I have tried on my pc because of the way it processes the packets. Hands down the best app I have ever payed for. DO NOT lose that unlimited plan..for the 30 a month it is you can't beat that for a mobile connection for your pc to the internet and alone that's worth having as an option. Again Jailbreaking FTW
If you mostly just use your phone as a phone and occasional internet access and are right handed the iphone 4 is great because of it's upped resolution and the array of sensors it has now gives it a lot more capability for apps.
Speaking of apps...the official netflix app if you have an account is FRIGGIN awesome. It converts all the Watch Instantly videos to play on the iphone and it looks great. playback is 10x on the iphone4 over 3g.
Also if you have comcast the app for that integrates right into your cable boxes , emta , voicemail where you can forward calls , check messages , and schedule program recordings and it has push notifications available.
Overall as far as the hardware I love the iphone4 minus the antenna location, if it wasn't for that it would be the best iPhone yet. Basically if you don't get 4 or 5 bars all the time where you are for most of your day...don't get the iP4 ...in fact go get a regular old 3g used, wipe it and jailbreak it , If you break it you always have a back up now and you can swap sim cards in them at will ... the iPhone 4 has a mini sim making phone swapping completely a PITA and that's only if you have or can get your hands on the tools or if you want to go down to at&t all the time. I could say so much more but I don't want to tread on the apple fans, just know that the iphone 4 is prejudiced against lefties and other than that it's upgrades as usual.