The Joy-Con can be used separately for two-player action, inserted into the Joy-Con grip like a traditional controller, held in each hand for left and right controls, or attached to either side of the Nintendo Switch!
Get it from Amazon for $299 (available in two colors).
Promising review: "I absolutely love the Nintendo Switch. The ability to play my games on both the TV and on the go is something I didn't ever really think was possible. The system design cleverly blends a table with conventional gaming controls that several others have tried, and failed, to do before (Nvidia Shiled Tablet comes to mind). It is easy and very satisfying to unclick the controllers from the sides of the tablet portion for use as either individual controllers, or to dock them into the included grip for use as a more conventional controller. Although the controllers are on the smaller side, I have not experienced any discomfort with extended, hours-long play sessions so far. Nintendo does make a pro controller for those who want something different, so your mileage may vary.
The tablet itself easily slides into the included docking station and within seconds is displaying game information on the TV. The included HDMI cable is a good length so I was able to connect to the TV with no problems. The included power/USB-C cord was likewise a good length so I didn't have to compromise on where I stationed the dock. Battery life has been about as expected for a tablet pushing out such high-quality games, and I have not had issues with running out of power, especially since you can charge via USB-C which I use for my phone as well. I have had a great time playing Switch so far (Zelda being one of the absolute best games I have played in years), and am really looking forward to many of the games on the horizon. I look forward to what Nintendo has to offer, and am thrilled with what I've got so far!" —Ted Gleason