It's interesting how much difference your choice of spec makes. Not just in terms of effectiveness, but also in terms of playstyle and fun.
Holy is boring me out of my skull. It's fine when I'm in a group, but is terrible when soloing. Judge/Seal every 10s, Holy Shock every 15s. Attacking only one mob at a time. I'm so looking forward to going back to Protection or Retribution.
I've also run into this same situation with a Rogue. I rolled a Rogue to act as a farming alt for Coriel, but I didn't like the way it was playing and abandoned it at level 20. Up till then I had been speccing into Assassination, with an eye on getting Mutilate.
I was thinking about picking the rogue up again, and I realize that what I didn't like about the rogue was that it moved so slowly while in stealth. I was avoiding stealth because of this, pulling with a gun, and generally not playing a rogue effectively.
So I looked at the Rogue trees, and noticed that there's a talent in Subtlety that increases your speed in stealth. One respec to Subtlety later, and my rogue is fun again, and I stealth all the time.