-The glossy back is too slick and makes holding the phone difficult.
Do you plan on getting a case for your iPhone? If so, why not get a case for the Lumia 920?
-The camera button is right where I place my fingers when talking on the phone.
This seems odd, when I hold the phone the camera button is gently resting in the palm of my hand, but I can't actually press it without using a finger. Do you hold your phone at an unusual angle or do you wear gloves or something while talking on it?
-The phone constantly disconnects/reconnects to wifi.
This seems more like a bug or something, I haven't seen this issue posted before (I use wifi exclusively and never get disconnected). The closest thing to it is the known fact that wifi disconnects 30 seconds after the screen locks, but this is going to be 'fixed' in a future patch: Microsoft changing Windows Phone WiFi behaviour in future update | Windows Phone Central
-Google mail doesn't sync very well.
Can you elaborate on that? What do you mean by 'not very well'? From my experience it's very seamless and easy, just sign into your gmail account on the accounts section of the phone and it auto-syncs everything within just a few seconds.
-Autocorrect is terrible.
Again, can you elaborate on that? What's terrible about it, what don't you like about it? If you are use to iPhone where the autocorrect changes the word you are typing for you, this may be something that's different that what you are use to. In WP8 it gives you suggestions/options that you can choose for the word, instead of the phone automatically changing the word you are typing.
-I don't like IE on it at all.
Again, what don't you like about it? I know that it's a super fast web browser, has tab browsing, and there's zero lag using it on the Lumia 920 when navigating, zooming ,etc. I'm not sure what there is to not like about it.
-My battery life is only about a half day of little to no usage, even though nothing is running in the background.
How long have you had the phone and how many times have you fully charged it? Also, have you turned off the Nokia Drive background task (this is known to eat a lot of battery). Many people are reporting great improvements with battery life after charging them a few times/days. Of course it could be you just have a bad battery too.
-It's just plain too big. (Although the large screen is GREAT for browsing/games)
Not sure what to say, the phone was available to test in almost all AT&T stores that I know of, unless you ordered online. Still, there were (and still are) a ton of comparison reviews/videos and spec sheets for the Lumia 920 and iPhone5. If it's too big then it's too big, but this isn't something that suddenly sneaks up on you; it either is or is not the first time you get to hold it.
-Lack of quality in the majority of third-party apps.
What apps are you needing that you can't find? What apps did you find that weren't up to your quality standards or the quality of comparable apps on other app stores? There are most likely very good alternatives to what you are use to finding on the iPhone app store. WP8 has over 130,000 apps, I think that's 'enough', especially considering WP8 only has about 4% of the market compared to its' competitors.
-No VPN support and apparently no Citrix Receiver.
Can't comment on this one, I don't use VPN or Citrix (and yes I know what they both are, I just have no need for them on my smartphone at this time).
Personally, assuming you've only had the phone for at most a couple of days I don't think you've given yourself enough time to get use to the WP8 OS versus IOS. It's a different OS, but much faster, more integrated and constantly improving.
If you really do decide to go for the iPhone 5, you might want to make a list of what you want/need on the iPhone 5 and compare that list to the Lumia 920/WP8. And then figure out which phone actually has what you need. From the list of negatives you listed above, most of them are items that take time to get use to.