The T4 OW lounge is quite old; but the champagne is quite fresh. However, I'd think they'd have decent food out. Starting an hour before boarding, it can get rather crowded.
No view of the runways from the lounge, though.
5-6 h in T4 OW lounge would get boring after a while. There really is not a lot to do in T4 entertainment wise. Plus, T4 is - ahem - under construction. It has lost its luster from the old days.