There were three more seasons of Justice League, now called Justice League Unlimted where the Justice League now comprises of around 50 superheroes.
Season 3/Unlimited Season 1 is prety hit and miss. Season 4 is probably the peak but Season 5 gives it a run fo its money. The biggest thing you need to know is that there are only 13 episodes each season, each episode is a stand alone story (for the most part). There are a a couple 2 or 3 parters. Season 4 and 5 have some great story arcs that span the entire season. The biggest thrill is seeing some rare superheroes that never get screen time...Atom, Atom-Smasher, Aztek, Black Canary, Blue Devil, Booster Gold, B'wana Beast, Captain Atom, CVaptain Marvel, Creeper, Crimson Avenger, Crimson Fox, Dr. Fate, Dr. Light, Dr. Mid-Nite, Dove, Elongated Man, Etrigan, Fire, Green Arrow, Gypsy, Hawk, Hourman, Huntress, Ice, Johnny Thunder, Metamorpho, Mr. Terrific, Nemesis, Obsidian, Orion, Plastic Man, The Question, Ray, Red Tornado, Rocket Red, Sand, Shining Knight, Stars, Starman, Steel II, Steel III, S.T.R.I.P.E., Supergirl, Vibe, Vigilante, Vixen, Waverider, Wildcat, Zatanna.
Some of these guys are only talked about, some are only seen in the background and without speaking roles, some get one shot in an episode dedicated towqard them and others are fleshed out in recurring roles throughout the series run.
Basically, you give up some story detail because of the allowed time but gain some major superheroes and even bigger fighting scenes. After Timm and Co. catch there stride in seasons 4 and 5, I thought they outdid there Season 2 work.
The other good news is because there are only get 13 episodes per season we may get the episodes quicker on DVD if they combine the seasons. Not sure if there has been any announcement on this yet.
to another Justice League fan. You will like what the future holds in DVD.