  We review some of the initial data from the UVOT telescope on the Swift
observatory. Statistics based on about six months of data suggest a dark burst
fraction of about 50% when combining both UVOT and ground-based observations.
There is evidence that some bursts have a large gamma-ray efficiency, which may
be due to strong magnetic fields in their ejecta. The bright GRB050525A shows
behaviour broadly consistent with expectations from the simple fireball model
for bursts, including evidence for a reverse shock component in the UVOT data,
and an achromatic break in decay slope indicative of a jet break. Other bursts
observed with Swift have a shallow decay initially which is difficult to
reconcile with the simple model. Replenishment of the forward shock energy by
continued ejection of material from the central engine, or initial injection of
material with a range of velocities, offers a potential explanation. In the
case of the XRF050406 an initially rising optical afterglow flux followed by a
shallow decay may be due to observation of a structured jet from a significant
off-axis angle.
