Unlike most expansions, TOB adds not only a whole bunch of things to the original game, but a whole new story, and a proper ending for the baldurs gate saga.
Harder fights, a new character kit, and one of the most suprising plot twists in history, all makes TOB a worthy addition to the series.

*story* TOB directly takes of after the events in suldanessar, where you deafeated the mage irenicus, and therefore regained your soul. Now, without a path to go, no wrongs that need to be righted you set of, to find out more about the bhaalspawn, and to find out more about your heritage.
Soon after setting out, the game begins, in a cold forest, with a dark voice foreboding a storm, with the knowledge about a fight coming your way, you ready your weapons and take a stance.
Everything takes off from here, and i guarantee that the story will not disapoint.
Soon, you'll find yourself in a city under siege, and a conspiration of the most powerfull bhaalspawn, but what are they after? Only time will tell.
10/10

*Gameplay* Same as always, the gameplay of the other games in the series are all intact, and are joined by some new spells, and some kick-ass high-level abilities.
A new addition is the wild mage, He can cast spells like a normal mage, but all spells he casts have a chance of going wrong. The mishaps often range from simple itches, the dropping a cow, or changing your gender.
A completely new dungeon is also added, the watchers keep, somewhere in the run-down tower is a ancient evil waiting for it's chance to break free, and the care takers are to weak to stop it. Watchers keep is filled with new items, enemies and challenges.
The action as i said earlier, is the same as always, point and click action is the order of the day.
The spacebar is still a major part of the game, allowing you to pause in the middle of combat to micro-manage your party.The romances that took place in SOA also have gotten a extension, giving a better ending to it all.
10/10

*Graphics* A little sharper than it's predecessor, and still with amazing spell effects and pain-staking attention to detail. The only major complaint i have is that some of the character models look a little stale by now, but besides icewind dale, this is how good isometric view games can look.
The character portraits are identical to SOA, by that i mean they still look good as ever.
9/10

*Sound*
The voiceacting is still as good as it can get, incredibly belivable, and a role-model for every other game.
The ambient sounds still sound good as ever, and have even gotten slightly leaner.
The combat sounds still sound a little....meh, but the combat music more than makes up for it.
10/10

*Value*
Around 40 hours of gameplay*wich is more than most main games* but it's tremendously replayable, and modding it with acension and repedemition mods will give it even more time.
This is defenitly worth your money.
8/10

well, overall this is solid as ever, and is one of increasingly decreasing amount of games you won't trade in the first few days of playing.
And, to quote any russian/asian salesman ever..YOU BUY!.