It's a really interesting system. I don't think I'd call it streamlined; there are too many knobs, buttons, and options for it to be simple.
It is pretty slick; iterative attack penalties are based upon your weapon skills instead of BAB. Lethal damage is dangerous, way more so that non-lethal. The core feature of classes really defines the character without pigeon-holing. All special abilities are feats or "perks". Good stuff.
There are a ton of optional rules: injuries, hit locations, etc. There are sub-systems for all your modern gaming needs (chases, seductions, investigations, etc.)
Mechanically, it's a long way from d20 Modern. That's not a bad thing, but don't be confused. It's d20 based, and uses hp (not vitality), and even pulled a lot of it's original inspiration from d20 modern, but it owes a lot more to True20 than it does to d20 Modern.
The setting books add whatever extra rules you need for the particular genre (supers, cyber-punk, etc.). They're well done, decently balanced, and the vast majority plays fast and smooth.
Character creation can be complicated, especially for some of the wierder settings, but is relatively easy.
Certain options (injuries) can really complicate gameplay, and should only be used when you really want to include them.
Feel-wise, it's a lot more SpyCraft than d20 Modern.
I hope that helped answer some of your questions.
