Someone had questioned the lack of reviews on this one, so I thought I might try my hand at a quick once over.
First, the obvious stuff. This is an expansion so I won't go into the basics of Pandemic, only how this might change the experience.
Now, to begin with, let's go over what ITL brings to your table. You get:
4 new roles
3 new events
2 new virulent strain epidemic cards
a new mutation challenge (2 cards & 12 more purple cubes)
new cards & research stations for a new 'Team play' option
a new solo play option
and finally, the In the Lab challenge, consisting of an additional board, 14 sequencing cards & 5 spiffy new cure vials.
Overall, a pretty nice set, now for more details.
First, the new roles. You only get 4, but they're pretty useful ones, and honestly if you also have OTB, you now have tons of options. I would point out that these 4 are by no means limited to ITL play, they should be nice options in all variants.
Second, the new events. Again, not a ton, but very nice ones that aren't limited to any particular variant. They match the ITL challenge thematically, but by no means would be out of place in other games.
I like the additional cards for the Virulent Strain challenge, though I admit I rarely play it. If you like the increased difficulty and want more variation, this will help.
I find the new way to play the Mutation challenge (Worldwide Panic, if I recall the title correctly) more to my liking than the original challenge. Essentially, the mutation starts with a wider area affected and spreads quicker, but I think this is actually a good thing if you combine it with the ITL challenge.
Team play is a nice semi-cooperative style where players are 2 or 3 teams trying to gain prestige for curing or eradicating diseases first. The loss conditions still apply to everyone, so I would assume some cooperation would still be wise, but it is limited. I found this part to be a decent option for play, but it didn't really thrill me. Much like the bio-terrorist from OTB, I can see it being a change of pace but not really what I would look for in a game of Pandemic.
The solo rules are an interesting take, if only because I would bet most Pandemic players already play it solo as is. It allows you to take 1 role and play a modified game with a CDC helper that takes very limited actions to assist you. I think this might grow on me over time, having only tried it once, but I still prefer to just control multiple roles when I play solo. Still, I do love options to keep things fresh, and this is a pretty good one.
I've saved the biggest thing for last. 699
The Lab challenge is a leap forward in a game I already loved. It is a major change to how you cure diseases. Now, rather than collecting a set of cards and discarding for a cure, you will collect samples, sequence and characterize the disease structure, testing your cure before finally having it cured. This is a lot of extra actions, and it takes some getting used to, but I found it to be leaps and bounds ahead of the base game for theme. You do feel like you're really working at the lab work to find these cures.
When you perform a treat disease action, you may collect a sample for your cure. That is, you may transfer a cube to the lab for use rather than back to the supply. A disease sequence will be found and anyone in a lab may play a city card to characterize the sequence as a specific color. Later, as the sequence is worked on, a player in a lab may play an additional card of that color to test the cure, removing one cube from the board in the process. Lastly, a player in a lab may play the remaining cards needed for a cure, with the same results as in the base game. This is a long way to say that you will still be using 5 cards to cure, but it can be spread out among the players with greater ease. The trade-off is the lab work will consume a lot of actions. You'll find players won't have to rush off to particular cities as much to trade cards, but they will congregate around research stations as they work on cures. This is a variant that makes stations a bigger priority, but it isn't like people just ignored them in the base game.
Overall, this is a great expansion. Like OTB, there are things I may not use every time, but nothing is a waste and there are parts I personally wouldn't want to play without. The theme and challenge of the lab work is what sells me. 699