Just my opinion:
I started seriously detecting 2 years ago. As a newbie, (which I still consider myself), I had the same question about the AT. At the time, I wanted to upgrade to a more serious detector in the 6 to 7 hundred dollar range, which at the time was the AT. I was using a Titan 3000XD, basically a Radio Shack type machine that was nothing but a bell tone detector. But it was enough to get me hooked on the hobby.
So I bought the AT PRO, and a 5 x 8 coil after the AT user's recommended it, especially in trashy area's which is mostly where I detect in my area.
I knew there was going to be a learning curve, seeing that the technology had changed over the 10 yrs. from when I bought the Titan, but really I went into it not thinking that I even knew how a detector worked, so I just got it out there and started swinging away, remembering the tips and tricks from T-net user's, and youtube vid's.
So, probably like most newbie's I went out thinking that the old coins, and gold, were going to be flying out of the ground and into my pouch. Well that didn't happen, but it really didn't bother me, because where I hunt, I usually recover relic's from the past, and soon I was more interested in that then the coins and gold that were more valuable, or could be stated, "the happy dance moments".
After 2 years of using the AT, here's my take:
You have to take the time to learn it. The number's on the VDI are number's, but more importantly the sounds are the key. That was the first thing I noticed, was that other then one solid tone from the Titan, the AT actually changed in volume and sound when you passed over a target. Like a bottle top versus coin. The bottle top would sound great until you got to the edge of it, and instead of the sound dropping off a cliff, you get a slight fading, followed by a little grunt. Where a coin, the sound would drop off the edge. Just a whole lot more info coming from the new technology then the old. And I'm clueless what a more expensive machine can do that has multiple frequencies.
I haven't had any physical problems with it, maybe because 99% of the time I'm swinging the 5x8 coil, which is far lighter then the stock coil. I'm 60 yrs. old, 5'8" and 145 lbs. dripping wet, which I don't know if that make's a difference. Seem's to be well balanced for me, but just my opinion. I know the Titan was alot lighter but not sure if that's because it's a straight shaft.

Hell, I have more pain from the constant up and down of digging! Just I side note, I'm only able to get in maybe 300 hrs. a year detecting, not like some that do it every spare moment.
Sorry, looks like I'm rambling.
"Is the AT pro really that good?"
Finding targets? Excellent! But then so was my Titan.
Giving me a better understanding of what may be in the ground? Excellent, but had to put my time in learning what it's telling me.
Has enough bell's and whistle's? Plenty for the hunter that know's the difference between what the machine know's and what the digger know's about the machine.
IMO, location is the key obviously. Case in point from yesterday.
I have a couple of farms where I've spent most of my time. Certainly not coin factories. I alway's pass an abandoned baseball field on the way there. I've never hunted a park, and decided on the way back from the farm, to stop and spend a couple of hours. 13 clad in about an hour and a half. It was just yesterday, that with out knowing it, I had learned alot from the AT. There was no question it was a coin other then once (pulltab). 3 clad and a 1835 LG from the farms over 2 yrs. and honestly that was probably by accident because alot of old iron will ring up as coins

. Is it that good? Only if the stuff is there

.
And finally, I have no doubt that there are other machine's in the price range, that are just as good, but that's the nature of the beast. You know,
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AT's been a great teaching tool for me anyway. Put your time in.
Good Luck!!