NetHack

Is better than AngBand. So there. Also, the best proof that graphics don't make the game.

That would imply that NetHack is a good game.

• And NetHack is not a good game. NetHack is a great game.

Has everything including the kitchen sink. Unfortunately just about everything in the game wants to kill you; people may play for years and never get further than 10 levels into the dungeon (that was me, until I stopped playing wizards -AdamField). It's a heck of a lot more complex than AngBand, which is not necessarily a good thing. Certainly both are good games; I happen to think personally that the easy modifiability of AngBand (and the resulting slew of variants) makes it better than NetHack, but then again I'm biased. - ChainMaille

• AngBand is a hack-and-slash dungeon crawl. NetHack is a dungeon crawl, but is a lot more about finding out obscure game features and using them correctly. If you want to finish NetHack in a reasonable amount of time, go look up the spoilers on the web. It will still take you many deaths before you Ascend, but it reduces the learning curve from years to weeks or months.
• As a result of the massive number of little features and the ad-hoc way that they were added, the NetHack source code is apparently rather tangled. So if you're interested in hacking a roguelike, then you'd probably not want to try it. Heck, it might make a good example for CS70...