Some have brought up good points and if I wasn't clear enough in the OP, this "review" if you will was entirely my own personal experience and bias. Some may not face the issues I have and be perfectly happy with the platform. The phone itself is one of the best I've ever used, I'd say I like it more than the Note 3. My biggest gripes were the ones listed in the OP and if MS is able to resolve those, I'd happily stay with WP. However, I'll be starting residency soon and I depend on some key applications and in order to stick with WP, I'd have to carry a secondary device (e.g. old ipod or used iphone) which kind of makes it cumbersome, especially if I have to keep it tethered.
About multitasking, IM+ loses connection and doesn't properly keep track of messages when I hit the start button. It returns to the previous conversation and buffers the missed ones but many times it misses out on the messages. Skype doesn't retain the last conversation, I have to go back to the user manually. Kindle only retains the book/page you were at for a limited time before timing out and sending you back to the home page. These are just a few of the apps I've run into issues with, there's some more as well.
However, the point about it being the fault of developers is probably spot on and I don't contest that. But for an end user, that doesn't really matter does it? MS should have strict standards that these developers have to adhere to so that multitasking is consistent and not app dependent. Android of course is far from perfect but I did have better experience multitasking with it.
With regards to AT&T, some have argued that they made prices more feasible for the masses and while that may be true, they earn that money back through locked contracts. Furthermore, it's hard to argue against Nokia/MS deciding not to sell the unmolested version of the phone at full price via online and their MS store. This would have given ample choice to everyone: Go to AT&T for a subsidized phone or if you want the full 1520 experience, go straight to MS. It would have been win/win and the only reason I can see this not happening is because AT&T forced Nokia's hand.
@manicottiK you're right, "badly needed" was a poor description for the select all feature. Rather it is a needed feature (for me and probably some others) and should not have been left out when they implemented copy/paste. I often find myself scrolling up and down to select all the text on a page and it ends up being pretty cumbersome. It wouldn't have been difficult for MS to add in such a simple feature.
I'm not 100% committed to the Note 3 yet but was contemplating the move. I may hang on until April when WP 8.1 is released + the rumored Apple phablet comes in May so it will be a good time to make a decision then about whether to jump ship or stick it out. I do hope that the OP helped give some insight to those that are thinking of committing to WP. I personally would like to see Microsoft become much more nimble with faster updates and have them prioritize WP development by throwing more money at developers to offset their losses due to the small US marketshare. Obviously WP is making nice headway in Europe so the momentum is there.