I lived in Kansas City most of my life. Here is my take on living in Kansas City and building a start-up here.

1. Climate.
There is no mild weather in KC. Summers are excruciatingly hot. Winters can sometimes be very cold and snowy. Tornadoes can get pretty scary at times, but 90% of the time there is nothing to worry about. I've seen a couple of touchdowns in 15 years. Most of the time i just hear about them.

2. Cost of Living.
Rent is fairly cheap. If you're single and want to be in the middle of all the action a single bedroom place on the Plaza will probably run you around $800. Power & Light district will likely be around the same price. Westport area is going to be cheaper around $600. If you don't mind the drive, you can probably find a decent place in North Kansas City for around $500-$600. Want to buy a house? ~$250K in the burbs for a nice 4 bedroom house 20 minutes away from the center. 2-3 bedroom homes are around $160K-$200K.

3. Traffic.
KC is backed up all over the place between 8-9am and 5-6pm. When the rush-hour is over, it is a pleasure to drive here.

4. Nightlife.
You have the new Power & Light district with tons of bars and clubs open 24/7. You have the old Westport area with it's own vibe. If you're from the Bay Area, you'll likely fit right in here. It's a very hip place. Plaza, Zona Rosa and The Legends are great place to shop and get a bite to eat around day time and up until midnight. KC occupies pretty massive territory, but it actually isn't a big city and it can get old pretty quick. So keep that mind, especially if you're single or a young couple. You'll be running into the same people over and over again before you know it. :)

5. Recreation.
KC has beautiful lakes, nature and wildlife. 30 minutes away from the center and you're pretty much on camping grounds. Getting around on foot is pretty tough and even impossible in some places. You really need to have a car here. Sidewalks are non-existent in many neighborhoods. There is always something going on in the city. Lots of concerts and outside events in the summer. Not so much in the winter.

6. Tech Scene & Job market.
KC doesn't really have a good techy/entrepreneurial scene. It has strong corporate IT sector, which is booming. Good developers are still very hard to come by. Most companies are more than willing to dish out 100K+ if you know what you're doing. The interesting thing about Kansas City businesses is that most of them aren't looking for rockstars or ninjas. They're looking for someone who can fit in with the rest of the team. This is not a bad thing, but more often than not you wind up working with really incompetent people who fit in but don't know squat. It's also very hard to find interesting work. The hottest thing is IT jobs supporting internal development in financial and medical sectors. There are some prominent tech companies in the area like Sprint, Garmin, Honeywell & Cerner, but most are just not very appealing in terms of life/work balance, innovation and quality of work.

7. Want to run a start-up from KC?
Hmm... I don't know. Finding good developers is a pretty hard task here. Finding talented developers is inexplicably difficult. Most folks who know their craft are no longer in KC. You basically have to know people who know people. Tech conferences are usually full of talented folks. The great thing about KC is the lower cost of living. You can make a comfortable living on 60K/year, but as a developer you can easily make 100K here and have plenty of time & money to invest in your own start-up while working full-time elsewhere. So in that respect, it is a pretty good place to build a start-up.