My experience so far is that the casino bonuses are not worth it. I joined 2 sites this month (WH and EUcasino), and lost both bonuses plus an addtional £250. I was playing basic strategy BJ.
At WH admittedly I went on tilt after a bad run and raised my stake, quickly losing my £150 deposit plus the bonus, well short of fulfilling the WR.
At EUCasino I played more carefully, with a flat stake of £2, but still lost £200 by the time I fulfilled the WR for the £100 bonus. Perhaps I was just unlucky.
I'm not planning to do any more casino bonuses after these first 2 lost me money.