First off, don't introduce any fish to a tank that has ich. You're just asking for a loss there.
Next, any angel should only be introduced to a mature tank with lots of LR. They are voracious grazers and need LR for that purpose.
With all that in mind, I'd say that my Flame Angel has been a joy to have in the tank. I got him after my tank was running for about 8 months, and both he and I couldn't be happier. He doesn't nip at my corals, doesn't pick on my 2 Clowns, and will readily eat just about anything I feed him. Great addition, IMO.