I've been wondering this question for quite a while. After all, this is the racquet Rafael Nadal still plays with, despite numerous iterations and paint jobs over the years. Most racquet nerds in various tennis forums claim that Babolat ruined a good thing when they introduced the Cortex technology* in their racquets and that Babolat racquets “pre-cortex” is where it's at. I'm currently playing with the first Babolat Pure Drive without Woofer, Cortex, GT, FSI and other technologies that Babolat has introduced over the years and I'm really enjoying it so far.
So that's why I started pondering the question about Nadal's racquet of choice, the Babolat AeroPro Drive Original that so many hail as a legendary stick. I haven't hit with it frequently before, but I found one used that I'm going to take out for a serious play-test soon and see what all the fuss is about.
From the first few hits, the feedback you get on your strokes is more direct, which, if you hit it outside the sweet spot is a little harsh. I'm pretty sure that's one of the things Babolat has tried to work on for each iteration (if they've been successful is up for discussion): increasing the sweet spot and making sure off center hits don't jar the arm and still get back into the court. I personally really like the raw feel and find the information useful when I'm off on my groundstrokes, but I can see how it's not the most user-friendly racquet for intermediate players and can quickly become slightly painful for the arm. But this is on the other hand the complaint with most Babolats and should also be attributed to technique that needs work and/or bad string and tension choice.
TIP: Don't give up on your racquets until you try different strings and tension and possibly adding some lead tape or blu tack/silicone to the handle to change weight and balance.
Talking about strings, The Weisscannon Silverstring seems to work really well with the Babolat Aero Pro Drive Original, but I'm going to also try my current string of choice (together with the RS Lyon), the Solinco Hyper-G in it and see if I can get even more spin. Since the Hyper-G is a slightly stiffer string than RS Lyon, I hope it won't bother my arm too much.
No matter what string, what I really enjoy about the so called APD Original is the massive spin and whip you can get on the ball. It inspires you to go for the ball “Wild West Rafa style” and that sure makes for an entertaining (and sweaty) hit, although you should probably stay away from copying his technique too much or you might decapitate yourself or frame the ball into outer space.
Update: the Babolat Aero Pro Drive Original is a very good racquet, but a little too powerful for my taste so I'm staying with my Babolat Pure Drive Original instead (1997, non-woofer version). So I have a Babolat APD Original for sale in great condition. Let me know if you're interested in the comments.
What is Cortex? (from Babolat)
A CDS (Cortex Dampening System) interface transmits useful information to the player and the handle design brings that information closer to the player's hand for perfect control on every hit.