Overall, it is similar to the second season and I find no more good or bad episodes than in your average Trek season. The introduction of the Andorians, their the conflict with the Vulcans and the first pre Prime Directive stories counterbalance the Temporal Cold War plot as well as some mediocre episodes (Vox Sola or Terra Prime come to mind).
An important info for B&B bashers, their intriguing idea to set (part of) the season on Earth was rejected by the studio. "First Flight" shows that this was a mistake.
IMO, the quality between episodes varies strongly whereas the average quality difference between series is minimal.