I think it's safe to say that we're all DC Comics fans here, so it's not hard for us to look on the DC Universe and proclaim: "It is good." But let's take a look at what makes the DC Universe so special, shall we?
1. Superman. THE blueprint for superheroes. He has been called "the legend from whom all others have come." This is true for not only the DC heroes, but superheroes from any comics universe. Superman epitomizes all that is good and true about humanity.
2. Batman. The original urban avenger. Inspiring an entire group of non-powered urban warriors in his own world (Nightwing, Robin, Huntress, etc.), Batman is also the precursor to heroes like Daredevil--heroes who are born from some great tragedy and go on to do great good BECAUSE of that tragedy.
3. Wonder Woman. The first truly powerful, enduring female superhero. Though some maintain she is just a female copy of Superman, most realize she's far more than that. Wonder Woman embodies the traditional feminine role--tempered with the strength of gods.
4. Flash. The original speedster. Quicksilver and other speedsters would seem a little less interesting if Jay Garrick hadn't paved the way.
5. Robin. Predating even Bucky, Robin has the distinction of being the original teen superhero sidekick, a tradition that continues to this day.
1. The Superman "family." In pre-Crisis continuity, the "family" was a literal extension of the House of El. You had Superboy ("the adventures of Superman when he was a boy!"), Supergirl (Kara Zor-El, Kal-El's cousin), Krypto the Super-Dog, and others. Crisis was supposed to do away with this extra "baggage," but the Superman family had a mind of its own. Nearly all the elements of the old Superman family have returned, albeit in different forms. You can't keep a good family down.
2. The Speedster Lineage. Uniting DC's resident speedsters is the Speed Force, as well as an emotional bond almost familial in its strength. From Max Mercury (the "Zen master of speed"), to Jay Garrick, the original Flash, down to Wally West, currently the fastest man alive, the speedster legacy is in no danger of ending.
3. The Green Lantern Corps. Even though the Corps was destroyed by one of their own a few years back, this intergalactic police force has left a lasting impact on the DC Universe, which can be seen even now in the sole remaining Green Lantern, Kyle Rayner, who has taken it upon himself to recruit an all-new Corps.