I like the new GR86/BRZ, but I can come up with several reasons to avoid buying one right now.
I'll point out that I'm 37 years old and have owned 31 cars. I know these are amateur numbers compared to some of the heavy hitters on this board. With that said, of the last 6 cars I bought and sold, I sold 4 of them for more money than I paid for them (anywhere from $1500 to $3000 more), the other 2 I broke even on. The only way I've managed to support my massive addition/automotive ADHD is by buying them right, which frequently involves a fly-and-drive scenario. To say my wife is supportive is an understatement, she's probably closer to an enabler. I can't speak to what your situation is.
What I can say is the biggest reason to avoid buying a brand new car is the massive depreciation hit you would be taking in the event it's not what you're looking for. I'm not telling you anything you don't already know. A couple years into the production of the BRZ/FR-S, it wasn't hard to find brand new cars that were being sold for under in-voice... which meant the folks that bought them for MSRP (or above...) took massive depreciation hits. Fortunately, the resale on the twins has always been relatively strong compared to most cars, but a hit is still a hit. Waiting a while can save you thousands.
It's been mentioned above, but there's also early adopter problems to contend with... which, it's a brand new car, still under warranty, so I'm sure that's something you can look past if you love the car enough, but it's still something to consider.
Probably the biggest reason I would say to avoid this course of action is that you haven't driven it. All the reviews have raved about it, saying it's wonderful. I've driven hundreds of cars in my life and read even more reviews. I don't know how many times a particular reviewer loved a car (or seemingly all of them), only for me to drive it and disagree with them. It's all subjective, right? The last time I bought a car without driving it was a Civic Type R... all the reviews say it's wonderful and does everything well! I got a smoking deal on it (under MSRP- I had to fly across the country to find this deal...)... that car was a blast to drive! It was everything the reviewers said it was... there was only 1 problem: it caused me a massive amount of pain in my right knee and hip if I drove it for more than just a few minutes at a time. I adjusted the seat a thousand times, I adjusted the pedals, I even tweaked the lower bolsters/seat frame, in search of relief from the pain while driving... I managed to mitigate it slightly, but it never went away. I ended up selling the car, as it physically caused me pain to drive, which led to me not driving it much. I didn't lose a dime on that car, thankfully, but only because I shopped around and took a flight. My point being: the car was great. But the car wasn't great for me- more of an alignment problem with me. Honda made a great product, I would highly recommend the car... but I'm not going to pay that much money for something that physically causes me pain to drive. If I had been able to test drive one (there were none that anyone was willing to let me drive in my area), I would have been able to feel the pain/discomfort within minutes and would have avoided the hassle to buy the thing.
As such, I would say to drive the car before being sold on it. If you drive it and you don't love it, don't bother.
I would also ask: are you looking back on your old BRZ with nostalgia? Or did you truly love the car? If you truly loved the car, why did you really sell it? I'm not trying to be a jerk here... but I know from my own experience, there are a few cars I've owned that I looked back on with rose colored glasses, only to find that when I drove them again, they weren't as good as I remembered them. Have you considered at least driving another BRZ/FR-S in your area, to see if it was really as great as you remember it?
I've made the mistake of buying the same car more than once. Only to sell it again, in short order for the exact same reasons I sold the first one for. The only exception being the AP2 Honda S2000. I sold my first one purely for financial reasons. I loved that car. A few years later, I bought another one - a 2008 laguna blue AP2! I've now had that car for years and frequently say that you'll have to pry the keys out of my cold, dead hands. Barring a major financial crisis, I don't ever intend to let this car go again (especially with prices getting so ridiculous!). Every other car I sold and thought I wanted back, 90% of them weren't as good as I remembered them being.
Buying cars, especially new cars, is frequently an emotional decision. No amount of logic can make you stop wanting it once you've made up your mind. I can probably say the same thing about a long list of women I dated when I was younger. No one can tell you how to spend your hard-earned cash. Do what you want, brother!
With that said, from one car-junkie to another, I would make sure you absolutely love the car before going all-in. And when you do go all-in, buy the thing right, just in case. But I've owned 31 cars, I clearly have a problem... I might not be the guy to listen to in any capacity.