Predator was one of the first synths that I bought after my studio was broken into and everything stolen. Along with this synth, I also bought the Virus Powercore and Spectrasonics Atmosphere.
I ended up selling the Virus Powercore, because I found I was using Predator more often that the Virus.
Okay, I admit: that's a bit of hyperbole. The Virus sounds better than Predator, sorry. But the Virus GUI was much, much worse. I just wasn't compelled to use it, when Predator was there, inviting me to program new sounds... or tweak the bajillion presets. ...the presets, by the way, cover a LOT of territory and are all expertly programmed. I maintain RP is one of the best companies to buy from for preset sounds.
Anyway, the point is: the GUI is what makes Predator a great synth. Everything is laid out perfectly, there's plenty of power there, the modulation options are deep and interesting, and it just looks damn sexy, IMO. You want to play it, to program it. Of all the synths I've ever owned, I have written more patches for Predator than any other. ...many more, in fact.
As for the sound: I found myself most attracted to Predator's pluck sounds. Pads are... okay... not quite magical, compared to other synths in this class (Surge, Massive are better for pads). But for those really electronic-sounding, Berlin-school arpeggios, it's one of the best synths out there. In fact, the closest competitor IMO was Albino... and Predator definitely caries Albion's DNA: they sound very similar in character and soul. Predator has a little bit more "punch" to its arps, though: I suspect that behind the scenes, this synth is secretly adding a little PCM transient to the beginning of each wave and probably affecting the attack of the sound slightly to give it a little more "pop". For example, when I pull up Predator and Largo side-by-side and program the sounds from Predator into Largo, I get a much stronger attack on Predator. (In fact, I end up using the more complex envelope in Largo to match the attack a little more closely). ...By the way, Predator and Largo stack extremely well, I recommend it. Predator has a nice warmth to the sound where Largo has a more metallic quality, and the two together provide a lot of depth. ...You'll have to turn Predator's volume down, though: Largo's outs are not as hot.
It's also worth mentioning that Predator has a few neat tricks in its OSCs that give it more character than other synths (PWM on any waveform, for example). It's also good for simple FM sounds. The waves available make for some really great digital sounds, too: you'll get wonderful JD-like bell sounds out of Predator. Leads are generally very good, though (for reasons I can't put my finger on) I think I actually preferred Albino for leads. Still, passable. The effects are... okay. I usually end up replacing them with external FX, but they get the juices flowing.
BUT! (and it's a big but, I cannot lie, yuk yuk:) I don't use Predator anymore. [shrug] I don't. Never. ...I still have it installed, but I can't recall the last time I actually loaded it. I've become a Diva / ElectraX fanboy, mainly because these newer synths sound better. ...Quite a bit better. The filters have more depth to them and a (much) warmer quality. (The filters on Predator are... okay. The bandpass in particular has a nice quality to it that I enjoy.) ...I also find the digital sounds crisper in ElextraX, and Tone2's synth uses less CPU.
It's a shame, though: this is a wonderful synth, with one of the best GUIs I've used (I do wish patch-management weren't so old-school, I'll add), a great sound, great OSCs, great versatility. And RobPapen's company is very classy. I've contacted them multiple times for support, and they always replied within a day or so, and were very nice and very helpful.
...If Predator added a filter like Diva's, I would gladly and quickly go back to using it: the interface is wonderful and, as I said, I love the versatility of the oscillators. It was my workhorse synth for many, many years, and I love it. :)
Bottom line: it's a very powerful, very classy, surprisingly good synth... but it's getting dated. Not to wax philosophical, but: I think we're entering a new age of VST capabilities. I hold hope that Predator will get a major update and join the ranks of the new wave... but at the time of this writing, that doesn't seem particularly likely.