The resolution of the structure is reseanable, not very high. Maybe because the drops in their crystallisation trial were too small, only 2 microlitres of protein solution. So their crystals were not big enough, or affected by twinning.

The crystal structure give your an absolute answer about what it looks like, and are the most valuable piece of information for designing new drugs.

Article: The Crystal Structure of the Human Hepatitis B Virus Capsid

Molecular Cell, Vol. 3, 771–780, June, 1999

S. A. Wynne, R. A. Crowther1 and A. G. W. Leslie
Medical Research Council,Laboratory of Molecular Biology,Hills Road,Cambridge CB2 2QH, United Kingdom
(13 people working in this lab so far have won Nobel Prizes. 5 or 6 of them are crystallographers.)

Abstract

Hepatitis B is a small enveloped DNA virus that poses a major hazard to human health. The crystal structure of the T = 4 capsid has been solved at 3.3 Å resolution, revealing a largely helical protein fold that is unusual for icosahedral viruses. The monomer fold is stabilized by a hydrophobic core that is highly conserved among human viral variants. Association of two amphipathic α-helical hairpins results in formation of a dimer with a four-helix bundle as the major central feature. The capsid is assembled from dimers via interactions involving a highly conserved region near the C terminus of the truncated protein used for crystallization. The major immunodominant region lies at the tips of the α-helical hairpins that form spikes on the capsid surface.