I suppose if I never had the Kinect I wouldn't know how to miss it, but if my Kinect broke now, I wouldn't have to think twice about replacing it.
It's probably 50-50 on how I start up my games and the console. The voice commands come in handy a lot of time. By the time I've found the controller and sat down, I have the console and the game already running pretty much. Hell, sometimes I start up a game while still in the toilet
The more purposes you use it for, the more awesome it is. Skype is amazing with it, it's really awesome for media purposes too. It kinda feels archaic now to have to press buttons to pause the video, especially if you happen to eat something at the same time and don't have clean hands etc. Then there's the IR blaster part that is great. TV starting up/shutting down with console is great, so is adjusting volume, so is using Smartglass as a whole TV and DVR remote. Actual Kinect-games arnt much to write home about, but from personal experience Just Dance 2014 and Fantasia have been great, D4 will be free with Gold next month and I've heard that's amazing with Kinect too, but most others are pretty so-so I hear. As for non-Kinect games that still utilize Kinect, it really depends on the game. Some utilize it well, some less so.
It kinda depends on how tight your budget is. If all you do is game and you want to keep budget tight, maybe not get Kinect then, but I repeat, I'd really have hard time going to not having Kinect even if all I did was play. I constantly use Kinect to start up games, snap things, adjust TV volume, etc...
I'm probably repeating myself by now, but like said, I personally wouldn't consider living without the Kinect now that I'm used to it. The UI has come a long way though so that it works pretty well with just controller too, though.