The cover says it all really! (Although in this first season the actors are much younger than in the photo). Roma Downey (on the right) is an angel who's just been promoted from Search and Rescue duty to helping individual people with life's challenges. She's very loving and enthusiastic, but also inexperienced and naive. Della Reese (on the left) is her mentor - experienced, down-to-earth, and actually very funny.
Each episode involves a different case, and a different person in need of help and guidance, and there's normally a happy (or at least resolved) ending, conveying the message that God loves us. The messages of compassion and love and understanding are obviously compatible with Christianity, but also with many other religions, and I don't think Jesus is ever mentioned. So if you aren't Christian, you won't feel like the show is trying to convert you.
It's not exactly edgy, hard-hitting television, and nobody would consider it cool. But it's not really trying to be.
For the most part 'Touched by an Angel' is very watchable and always uplifting. It's not amazing writing, but it's affectionate towards it's characters and has a definate charm. Most episodes are good, some are not so good, and just too syrupy even compared to the rest of the show (the Christmas Nativity episode comes to mind).
I would recommend this if you want something comforting and uplifting to watch, and don't mind its super Americanness.