Kahoot!

Pros: So long as everyone has a phone and a decent connection, this makes for a very easy way to set up a game-style review session. Students always go crazy whenever this is brought out for class. It's simple to set up and use, and easy for the students as well. Great to bring out the day before a big quiz or test.

Cons: If not all your students have a phone, they can be embarrassed at having to bring up that they don't have one. Likewise, newer phones are faster and will have an advantage over older phones. Your building and areas internet connection will also have a big impact on how your session plays out. So, this isn't really good for areas with poor internet connection or high amounts of income variance where the range of phones with students will vary widely.

Overall: If you've got the internet speed for it and can accommodate all your students, this works great. Kids love playing and won't really think about how they're studying. Their minds will be more on winning the game. I'd recommend pairing victory with bonus points or physical prizes so the kids have something concrete to aim for. No matter the area, I'd still be prepared to have an extra phone on hand for at least one student possibly not having one to use. Just hide whatever you need to and offer up your own in this situation. For areas where smart phone ownership is less common, you can have students share phones by having rounds where certain students compete, then move on to another round with different students, with winners of each eventually competing in a tournament style set up. This just slightly changes the nature of the game and students will be focus on winning rather than that 4 of their classmates don't have phones. This will still be a problem if you can't get a phone to a student, so keep that in mind. This game won't work for all situations, but when it is a good fit for your class, it's an excellent, fun learning tool.

Pros: Easy to use & decent user interface
Interactive & fun lesson structure
Self paced learning
Good for tracking results
Great mobile app
Free version available

Cons: There should be more customization option & ability to create or add new game modes.

Overall: Kahoot! is a new kind of learning platform which converts learning into a fun gaming experience. It works great for schools & workplaces alike and offers a range of features to create different sort of questions like poll or discussion & even provides a way to track results be it an individual or team.