I think it's a good way in. If you do do it then make sure you have the right attitude. Give it your all and don't think that something is below you just because you're a trained pilot and are destined for 'better' things.
Now I'm on the other side of the door I see one or two crew trying to work their way up and their attitude toward working in the cabin is pretty poor and that they some how are too good to be in the cabin. I've also heard some current crew saying that one or two people over the years have had he wrong attitude, that they are above the job and it annoys crew and certainly won't go unnoticed with the flight deck.
I used the job to network to get a job as an instructor which I did and it just so happens at I was in the right place at the right time that my airline started an internal scheme and the rest is history as they say.