I bought a Nexus 7 tablet a few weeks ago as my first tablet. I got the 32GB wifi-only model. So far I have been impressed. The speed, display, and battery life are great.
I did run into one problem though. The headphone jack didn't seem to work properly. When I inserted my headphones, I would either get sound out of the tablet speaker or only one of my headphone speakers. And it would switch between these two, kinda like a bad connection. I tried two different sets of headphones and both behaved the same. I was disappointed in my shiny new tablet.
Thankfully, the solution (for me, at least) was simple. It turns out that the headphone jack is a tight fit and I just had to push the headphones in a little harder until I heard it click. Problem solved!
I have heard of a lot of other people with this problem that were returning their Nexus 7s. Hopefully this will help someone and save them from having to return their Nexus 7.