Watch it yourself and find out.
Personally, I think a lot of it was very of its time and hasn't aged well. Back in the 90s it certainly offered something that WWF and WCW weren't offering in terms of its gritty, grungy style, more edgy characters and hardcore spotfests (even if it copied a lot from FMW). That set it apart, and it being more "underground" gave it kudos and made you want to see it succeed. (I'm honestly not sure if zoomers get the appeal of the underground since social media makes everything mainstream and they're all big brand corporate boot lickers.)
I don't know why you'd want to go back and watch much ECW in 2025, though. It's very trashy and plenty of spots are whiffed. Companies like early ROH, TNA, IWA-MS, which were inspired by ECW, did a lot of the same shit but better, so I'd rather go back and watch them.