I went in 2013 and had previously been in 1999 at the old Rosenblatt Stadium. I would suggest getting a hotel closer to the ballpark if you are planning this well in advance. We stayed further away and it kind of took away from the experience.
Here's the deal with tickets, you can either go two options. 1) General admission where you stand in a line behind the outfield concourse and your seats while be first come, first serve in the outfield OR 2) buy reserved seats online through the NCAA ticket exchange that will be better seats but will cost more. We decided to have a few days of general admission and a couple games where we ended up buying reserved seats. Both were good options, but with general admission during the day it would get pretty hot sitting in the sun. During the LSU game that was during the day we just stood above the lower section near home plate and nobody cared, so that is an option as well. Also, the fans in the outfield sections are more rowdy and into the game than those in the reserved areas, especially during night games.
Another thing worth mentioning is that they don't serve alcohol inside the ballpark, but there are plenty of bars/restaurants in the surrounding area that everyone hangs out at if you want to drink.
Hope this helps, Omaha is a really pleasant city and the College World Series is definitely something worth going to for any baseball fan.