Not as good as it's predecessor but still a decent game.
The in ring action has been altered slightly to include tie-ups and a few weardown moves.
While the tie-ups are a nice addition, the weardown moves make the matches too easy which makes them end quicker. It's basically a test of strength where the two wrestlers will lock hands and try to push each other to the ground. It does it job at wearing down the opponent as it drains half his health meaning you only need to perform one or two semi powerful moves and you've won the match.
Apart from this matches are pretty tight. They seem a lot smoother than in Nitro and at a faster pace.
Some new matches have been introduced in Thunder. These include the 30 man Battle Royal, Cage, and Hardcore. There isn't an actual hardcore match but there is an option to have weapons around the ring which is essentially the same thing.
The main mode is the same as Nitro's Tournament but there are now 3 belts to go for. beating the tournament will unlock different wrestlers depending on who you win it with.
The roster has also grown a lot. Most of the unlockables in Nitro are now part of the starting roster. There are even more unclockables which include many WCW stars as well as fictional characters.
The graphics in Thunder are also improved. Not by much but it's noticeable. the main wrestlers on the roster now have FMV entrances a long with the Rants on the selection screen. There are more arenas to choose from, textures are brighter and more detailed and the games runs a lot faster too.
The pixelated crowds are still the same though.
Overall this is a great game with tons more features than Nitro but has a few flaws gameplay wise which brings down the fun factor a bit. If you enjoyed Nitro and/or are a fan of WCW this is still a good buy!