It is a good, solid frame. I have a 555SL Super Course. Not incredibly light, but not too heavy either. I think the bike (which has a 25" frame) weighs about 25 lb. Let me find the post... I think Raleigh 555 is thought to be relabeled Reynolds 501.
EDIT:
Here it is, from earlier this week. I linked to a post from an earlier thread.