I've played a couple of one-shots of Time & Temp over the past few weeks, enough to have some stuff to say about it.
Firstly, it is a fun and funny game. The combination of characters who aren't really good at anything with difficult to solve problems and time travel is just great. The system works smoothly, although it takes a few minutes to get into the swing of it (and I did make one major error in the first game, although it was easy to correct in hindsight, and it didn't detract from the game).
Coming up with scenarios is fun too! As the GM (General Manager) you really just need a time and place and something anachronistic to go on. My two games have been about the Dodo Liberation Front (eco-warriors going back to defend the wildlife of Mauritius from sailors) and a Norwegian supremacist who had gone back to the 13th century to create a high-tech Norwegian world empire. In both cases, the temps made good use of their "skills" to prevent both problems.
As GM, you do need to look over the paradox and challenge rules very carefully - there are a few things that aren't described very clearly. Check out the game's website - Ravachol has written an FAQ and some examples that help a lot in the understanding. I recommend checking those out too before you run a game.
Overall, great game - I really look forward to playing some more (and seeing what happens in an extended run).