So, how does O.L.D. / N.E.W / N.O.W. stack up against something like GURPS?
I am a fan of GURPS 4e and have ran/played it a lot. We broke up recently. Not because GURPS isn't awesome (because it is), but because it has all the crunch I want but in the places where I don't want it. So a) my enthusiasm for WOIN as the perfect rebound from GURPS may shine through
-D) and b) I'm going to focus on WOIN vs. a true contrast.
How does it stack up?
1) It's not AS crunchy (I know, I know, but bear with me...). It's crunchy in all the right places. You can customize gear, magic, starships and even concoct new species or careers. Skill rolls, combat and even character creation go considerably faster. The stuff an enterprising GM may want to do with a pair of ambitious players outside a regular session? Nice and crunchy wholesome fun. Actual play? Smooth and straight-forward.
2) Combat is wonderfully tactical without the same tracking, points of handling or system mastery. Now, the caveat here is that you can tune GURPS up to be a lighter game in combat. I would compare WOIN combat to GURPS lite, but with some cool new ideas (like getting pinned...). It's still tactical! You want minis and status markers of some kind (I use red magnets for PINNED!).
3) Skills are considerably less detailed. This is probably the "squishiest" part of WOIN. Instead of focusing on skills, the section discusses actions or "things people do often". :-D So, in that regard, it's more flexible. Skills can be more flavorful and descriptive yet broadly applicable as the GM pairs them with Attributes and adjudicates outcomes.
4) Health, Resolve and the Condition mechanic is way easier than GURPS HP/FP/Affliction tracking. Also more flavorful. Also more "cinematic" where the condition will "apply" but the hero will "shake it off" pretty quickly. It's a fantastic way to bring something like Anger or Pain into the make-believe without crippling the character. You all know it's there. But people can still kick butt and adventure.
5) Character creation is something I would consider doing as a pre-session in person with my group. I would never attempt this with GURPS. It simply requires way less point-squabling, hand-wringing and GM oversight.
I think one of the coolest parts that sets WOIN apart for me anyways, is the generous OGL and the WOIN marketplace. I can't publish my own stuff with GURPS. I can get all the right crunch and publish my stuff with WOIN. This generosity IMHO warrants my support.
P.S. I am not discouraging anyone from GURPS. It's an awesome game filled with brilliant stuff. I am not saying WOIN is better or worse; instead I believe WOIN has some merits worth considering for someone who wants a solid "medium" crunch game.