Edward Ingold , Oct 30, 2010; 11:28 a.m.
For some, an electronic viewfinder may be sufficient. For others, an optical viewfinder is the best choice. With an EVF, you have a smaller, lighter, quieter camera, but suffer from low viewing resolution and a significant time lag. You usually lose the advantage of predictive focusing (q.v., phase difference focusing), found in most DSLRs.
Not all DSLRs are the same with regard to the quality of their finder. Prisms are brighter than mirrors (and heavier). Some have more eye relief than others. Some show more or less of the final image. 100% finders are usually found only in the top models, and may be overrated (IMO).