Depends on what you want to do. No office word as to the performance increase for Haswell. I think it will be less than 10% compared to Ivy Bridge because Intel is focusing on lowering power consumption; assuming same clockspeed.
We all need to wait until around May to find out what the performance increase it. If you can wait, then wait if you can't wait then buy now. I'm waiting for Haswell before buying a new laptop.