Others say...

"broken game"
I don't know about broken world; I would call it broken game. Its very frustrating that you can't import characters from DS2 in any meaningful way. I enjoyed DS2 a lot, and just wish that broken world worked as suggested by the documentation. There's no mention of patches on the official site.

"The fun continues"
I am really enjoying this game.

I never finished DS I, I thought it was tedious. DS II fixed the problems of DS I and I played the sequel through to the end. There wasn't anything about the gameplay compelling enough to make me want to go through it a second time for the extra charactor slot, but it was a REALLY enjoyable H&S while it lasted.

I haven't experienced any of the bugs the one reviewer did, my characters imported right away. I'm having fun well into the second act.

If you enjoyed DS II, you should buy this.

"Dungeon Siege 2: Broken World"
The game was extremely short. Even with the 2 new characters and weapon recipes, I did not think the game was worth anywhere near the money it cost.

"Much buggier than original DS2"
The worst bug apparently is limited to importing characters from original Dungeon Siege 2. Many (truly) folks, including me, can't even play the game because there is a limit to the number of characters, and this bug prevents you from switching characters in your group. For example, I tried to play a multiplayer party mode in which the limit was 3 characters. One early quest requires you to make a dwarf a member of your group. When you need to get your original party members back, the only way to do that is to release this dwarf to the Inn. When you do that, the game quits and when you start again, that character is gone from the game. There are many other problems related to this bug. This happened with both of my imported DS2 characters.

I would normally expect a patch to resolve this problem from the developers, but apparently the thinking is that this won't happen unless you import corrupted save files. My understanding is that they have not been able to figure out how these files get corrupted, even though they have been trying a long time. So I will be pleasantly surprised if they do find a way to fix this problem, but I'm not holding my breath.

In my opinion, the quality of Dungeon Siege 1 and Legends of Aranna was much better than anything after that, and Broken World is aptly named.

"More of the same, which is good"
This is essentially just a new set of missions, along with two new character classes and a couple of new pets. There are also new item recipes. This extends a pretty fun hack and slash game. You can import parties from the original or start with new characters at the appropriate level. Unlike some expansions, this starts out at a difficulty level appropriate for characters who've beaten Valdis. I'm enjoying it.