Worms Reloaded marks the series' long-awaited return to the PC in 2D form, but is largely the same offering as the Xbox 360 release of Worms 2: Armageddon. The game sports full Steamworks-integration to handle multiplayer, stats, and achievements.
Personally, I'm sad to report that the game could have stood to evolve a bit with this new PC version. I'm not sure what could be done to the Worms formula at this point, but it's a too close to what I played 10 years ago. The HD graphics help, but a few new modes and weapons don't really make this game stand out from Worms Wold Party or Worms Armageddon.
There are a bunch of modes to play, including two campaigns and a mode that pits a single worm against an infinite amount of enemy worms, but the real value is with the multiplayer, which supports 4 players on the same computer or online.
There are a good amount of modes available online ranging from competitive, ranked play to goofy, just-for-fine variants. Since the AI isn't all that fun to play over and over again, your enjoyment of Reloaded will likely depend on your willingness to jump online.
If you've been playing the Worms console releases, you won't find a lot of new content here, but if you've been missing Worms and do not mind the old gameplay, this is what you want. The game hasn't really evolved since its previous 2D incarnations, but Worms: Reloaded is easily the best way to play multiplayer Worms on the PC in 2010.
If you've somehow never played a Worms game before, this should serve as an excellent introduction to the series. You probably won't find it outdated, too!