Battle out of Hell provides a few great levels, but the creativity dies out towards the end.
The Bad: Level design feels stale towards the end, sporadic level design, exactly the same as the last game
The first game rose to great acclaim due to the excellent classic FPS action, rocking soundtrack, superb weapons, and varied enemy and level design. Battle out of Hell is the expansion that picks off where the last ended. You are ascending out of Hell to stop Alastor who is trying to create a massive army to take over Heaven. While the story doesn't do much but conclude the last game it's pretty bare bones.
The expansion adds 10 new levels and two awesome new weapons. The new weapons are a sniper rifle that shoots spears and the alternate fire is a bunch of bombs that can bounce around. The second weapon is a machine gun with the alt fire of a flamethrower. Both weapons are useful and very fun to use in combination with the already excellent arsenal. The action is exactly the same as the last game just with new enemies and levels. Some levels are really short while some drag one for quite a while so the game feels a bit sporadic and badly paced.
The new levels are awesome such as the Orphanage, Loony Park, and Lab, but after those three the creativity dies down quickly. The Loony Park features a full roller coaster ride while you shoot enemies and the Orphanage is really spooky with creepy kids that you kill. After that the levels just feel like generic hallways with different designs. My least favorite were the Colosseum and Stone Pit. There is one level that is only available on Nightmare difficulty. Other than that the multiplayer adds some new maps, but once again, no one plays online (stick with LAN).
If you really love Painkiller or never picked up the expansion you're missing out on some really great shooting action, but it can wear thin towards the end, especially the story.