I have these chairs! DH and I love how they look--we have the Terra dining table from West Elm as our dining room table and use two benches and two of the chairs for seating. We don't have cushions for them at the moment, and they are reasonably comfortable without them. DH's mom is probably going to make us some cushions, so we decided not to purchase the ones from West Elm. I think the cushions aren't an absolute necessity, but they're nice to have.
The quality of the chairs is relatively good. We had no issues putting them together, and they have held up well so far. We haven't had them for very long, though, so it's hard to make a prediction as to how they'll hold up long-term. We also have the Overlapping Squares counter-height barstools, and we did have some issues with the quality at first. Apparently, the barstools are made at a different factory (in Vietnam instead of China, where the chairs are made), and they have had some quality-control issues with that factory. We had to send a couple of the stools back because manufacturing defects were making them impossible to put together. The replacements we received were fine, and as of the moment, we are satisfied with the barstools, too.