SPACI score report for 3is8 in ASTRAL 2.03:

PDB Entry: 3is8
SPACI score: 0.41
AEROSPACI score: 0.41

Experiment type: XRAY
Resolution: 2.25
R-factor: 0.179
PCK1 PROCHECK Ramachandran: 1
PCK2 PROCHECK Chi-1 angle: 2
PCK3 PROCHECK H-bonds: 1
WCK1 WHAT_CHECK Packing: 0.861
WCK2 WHAT_CHECK Ramachandran: 0.674
WCK3 WHAT_CHECK Chi angles: -2.134
WCK4 WHAT_CHECK Backbone: 1.818

Note: Here are links to pages about PROCHECK and WHAT_CHECK.

Here is the full WHAT_CHECK report on this protein (linked from the WHAT_CHECK site).