With about a month of astrometry now in hand, the orbital solutions are converging on a perihelion date close to March 11, 2013, and perihelion distance of close to 0.3 AU.
How bright Comet C/2011 L4 (PANSTARRS) will be is still very much unknown, and we may not know for more than a year how bright it will eventually be. The ephemeris from the JPL Horizons website has a predicted peak magnitude of -0.5, and the Minor Planet Center predicts a peak magnitude of 0.6. When the comet is brightest, it will likely be low in the west after sunset, about 10 degrees above the horizon at 7pm seen from Hawaii.