I have a scarce few pop evangelical songs I still like from days gone by, but in general I've become rather put off by how shallow, sickly sentimental, and "Jesus-is-my-boyfriend"-like it has become. And an increasing number of pop evangelical songs really have nothing particularly Christian about them at all.
Many years ago I had occasion to speak with someone who worked on the production side of the Christian music business (I believe he was with Jennifer Knapp, but I don't remember exactly), and he said that most Christian music (not all, but most) is written solely to elicit an emotional response. The big boys actually do scientific studies to determine how music affects people psychologically, and work it into their music. The indies absorb the same trends and follow suit.
I don't think that means there is anything inherently bad about listening to that sort of music, but just realize that you are probably being emotionally manipulated; meanwhile Orthodox music is generally dispassionate. Whatever emotion there is flows from what is being expressed, not the combination of soaring notes, acoustic guitars, and bass.
But I do have a soft spot for old-timey, pre-pop music. Classic hymns are wonderful in my opinion—give me good Protestant organ music and I'm happy!
I would also be careful to avoid music that is theologically horrible. Some [perhaps unwittingly] have good parts. But there's also questionable or cringe-worthy ones. Music is a powerful teaching medium, a painless way to accomplish rote memorization. ("I don't listen to the words!" "Does that mean you don't hear them?") Most are not swayed that easily, but even creating a sense of sympathy for things can be problematic long term.
I find that pop evangelical music often focuses a lot on hopelessness and endless searching, which probably reflects the internal state of Protestantism today. Speaking generally, I would call this kind of music spiritual soda and fries (I couldn't even call it milk, really). Soda and fries are fine occasionally, but it's not something to consume frequently.
That having been said, I also have some issues with the concept of listening to proper Church music as entertainment, divorced from the divine services. The age of multimedia presents interesting possibilities. I suppose that evangelical pop music may be the modern version of folk music—whose theology, when expressed, wasn't policed either. So I don't know. It's a choice for the individual to make, but personally I don't find much value in evangelical pop music, much less secular pop music. I have always preferred a good symphony, or Church music that was never intended to be used liturgically (such as Rachmaninov's All Night Vigil).
Anyway, that's my bag of wind on this subject.