I've been playing almost non-stop for the past two days, and I think it is absolutely brilliant. However, this is the first Pro Evo game I've ever played, so I didn't go into it with any prejudices or huge expectations. I didn't play PES '08 or '09, which were apparently a disappointment to most, nor did I play any of the PS2 games from what were apparently the glory days of PES.
The first time I ever even laid eyes on PES gameplay was when I started up the demo. I played both the FIFA10 and PES2010 demos extensively, initially thinking it was a no-brainer and that I would buy FIFA. But the more I played both demos, the more certain I became that I would get PES. FIFA may have the smoother animations and more precise control (though I actually prefer the controls in PES) but Pro Evo wins hands down in the gameplay department. In my opinion, it strikes the perfect balance of realism and fun (it is a game, after all), and its virtues far outweigh its flaws.
I can certainly understand why people are so divided over this game, though. I know what its like to have followed a game franchise year after year, expecting or wanting certain improvements and not getting them, or not seeing the game evolve the way I would want it to. If I had played previous versions of PES, I might feel completely differently than I do now. I don't think I would, but who knows?