I'm of the thinking that it's impossible to truly form a good opinion of it without some deep editing and time with it. Last night I spent quite a bit of time reading the manual and trying to wrap my head around some of the new stuff involved in the cabinet section alone. I went through the presets and as always, I tend to hate most presets (especially for hi-gain amps), but even with that said, they are immensely better than they were in AT2 of any form - but, when I took some of the presets and did a little tweaking for my gear I was able to get a tone that made me smile. But back to the point - I have a hard time seeing anyone dismiss this product after less than a day with it - I almost did that with GR4 and while it took me a while, I'm of the mindset that it was a great advance over what it replaced and I'm sure Amplitube 3 is a great advancement over Amplitube 2. Get intimate with it guys, get down to the level you would if it were a real amp, mic, pre, room, effects - it's a complicated beast of a product that will take time to learn the ins and outs. Also - look to it for more than just hi-gain - it's got some great other uses at least to me as I don't only toy around with the 5150 model.
Just my 2 cents. Write it if off you want, say the free options are better (for you they may indeed be), I have a feeling AT3 is going to get some great use for a large group of people making music not only in metal but in all genres of music.