I came from a 4S as well (Verizon) and I felt the data on Verizon in this area is painfully slow. AT&T is definitely faster...so moving to a 4G device has been a welcomed change.
One of my highest priorities is having a phone that can get me through a FULL day no matter what I throw at it, and this Maxx does the job. Prior to the iPhone I'm not sure if I would have ever even considered a phone with a non-user replaceable (swappable) battery. I'm glad I spent time with the iPhone for a lot of reasons, but that's a big one...it showed me I can live with a non removeable battery and gave me the ability to "trust" enought to give the Maxx a try.
I love that I can open something on the Maxx and I can share it no less than 10 different ways (email, gmail, text, read it later, instapaper, copy, send....the list goes on and on and is only limited by what apps you do not have).
And my experience has been opposite of the OP...I find my phone holds a signal where the iPhone did not. However I live in a decent 4G coverage area. In my building at work the iPhone spent the entire day fighting for 3G signal. The Maxx stays on 4G solidly (though lower bars). We recently got wifi at work so I no longer need to worry about it, but I thought it worth mentioning for those of you that expressed concern about the "worse signal". I respectfully disagree with the OP saying the Maxx has a worse signal than the iPhone.
I have been pleasantly surprised by the Google dictation (built in)...it seems as capable as Siri for dictating messages, and honestly has more overall functionality than I realized. You can do internet searches, send yourself a voice memo, send a text, etc. So while Siri was a fun thing, the daily functionality you might use it for is really already there on the Maxx.
I had a hard time giving up the overall "support" of the iPhone...I agree with other posters that if there's going to be only one app made for a given functionality by a developer, they do seem to make it for the iPhone and not Android. And worse, if they do decide to support Android but built it for iOS first, very often it's a port...and a poor one at that.
The Maxx has been rock solid for me. I had a Droid X that I grew so frustrated with I ended up with the iPhone. The problems I had with the Droid X are non existant on the Maxx. I have never had a spontaneous reboot, (though I did have ONE freeze). But the point is, the Maxx just works. And it gets me through a full day no matter what I do with it. The Maxx gave me confidence in Android that I had lost.
Yup...I love my Maxx. And for the record, I have a Macbook Air and an iPad 2...so having the iPhone firmly put me in Apple's ecosystem. I'm enjoying being within that ecosystem, but having something with different functionality as well.
ETA: I should probably have also mentioned...I've had the Maxx since January 27th when it released. So my opinions are based off of 2 solid months of use. And I am so NOT missing the 3.5" screen on the iPhone.