I run over to Killeen every once in awhile. I have friends and clients that own businesses and work there. A few live there.
Most of the previous comments are true. Killeen is not the prettiest place in the world. There is nothing quaint, historical or charming about it. It supports the world's largest military base. If you like listening to artillery all day and night it's your kind of place. I suspect just about any location near Fort Hood will provide you with a nice battlefield background noise (even in Temple, Belton, and Gatesville).
The upside is that it has a booming economy. The Killeen/Harker Heights/Copperas Cove area probably already has 1000 housing starts for this year. Neighboring Lampasas county was supposedly the fastest growing area in the country last year. There are tons of franchise restaurants, car dealerships, and motorcycle shops. Guns Galore (nothing special about their prices, but they have a pretty good selection - especially handguns - and they're nice folks) is only gun shop I'm familiar with over there. New schools pop up all the time. It has a new Killeen/GAA airport. It's only about 15 minutes from Temple which has a large VA as well as Scott & White and King's Daughters Hospitals. Lake Belton and Stillhouse Hollow are nice nearby lakes for boating and fishing.
It seems to have quite a bit more violent crime that than other communities of equal size.
Having said all that, I could live there. It wouldn't be my first . . . or second . . . or third choice, but I don't think it's the worst place in Texas to live. Marble Falls is nice. Salado is nice. If you like Hill Country (hills, trees, winding roads, scenic rivers and lakes), there is whole lot of nice from just south and west of Killeen all the way down to San Antonio and west to Junction.
http://www.txinfo.com/products/hillcntrymap.html
Way east Texas is flat with a lot of tall pine and cypress trees, some areas are foresty and others are swampy. Pretty much every thing in between east Texas and the Hill Country is flat or gently rolling farmland. There are some nice areas out here where you can buy land that is not too expensive.
West Texas . . . you probably don't want to move to west Texas . . . or deep south Texas, or the Panhandle.
I guess without knowing more about what kind of area you're interested in, what kind of city comforts you want or don't want, what you plan to hunt, or how much you're looking to spend, that's about where I should stop.