it is not bad.
out of JFK, this is somewhat typical advance purchase pricing for a one way (B6 Mint is $599 one way advance purchase).
since UA has moved ps to EWR, their fares are out of line with the NYC-SFO/LAX market (which is what they wanted to achieve, but i digress), so looking at it purely on an EWR-SFO basis it's an excellent deal. on an NYC-SFO basis, it's not outstanding, but also not terrible by any means.