I split attendance between Baptist and Church of Christ for a lot of my youth, and did some stuff with a CoC college group during that time in my life, because they were the best/most welcoming of such groups on my campus. When I go now, I usually go to a "true" non-denom (I don't consider CoC to be in that category, although that's debatable), or occasionally a Baptist or Methodist church. I pretty much never go to CoC anymore, so one could say I sort of "left" that church.
Why? Mainly prevailing attitude, at least here in my particular part of the south. CoC is pretty much the most "doctrinal" and legalistic of all the available protestant churches here. The prevailing belief is that only CoC will go to heaven; they seem to have some sort of subliminal "new children of Israel" complex or something. They don't cooperate at all, as a rule, with other churches. In my current tiny town, 1st Baptist, 1st United Methodist, 1st Presbyterian, the CoC, and an Episcopal church are all on the same block. All the other churches, at least once a year, hold a big community service together. All, that is, except the CoC. Trying to get them to fellowship at all is like trying to extract blood from a stone. The Episcopals have beliefs MUCH further from the others, and they love to get together and break bread with everyone. It's wild, but not an isolated incident, in my experience.
They just seem to be a pretty poor example, in broad sweeping strokes, of a "Christ-like" attitude. I see them as basically pharisaical in general terms. That is, in fact, sort of their nickname. If anyone says "the Pharisees," everyone knows to which church the speaker is referring.
That said, I know many friends who attend and believe in line with CoC that do not follow this pattern at all. Like, complete 180. If a particular CoC happened to be full of such people, I wouldn't mind at all going (to the extent I go at all these days).
Last time I attended? Probably age 20 or 21.