it's quite easy. If you are in Play mode (hold the rightmost switch for two seconds), just tap the switch once to see the current BPM setting. A nice feature: While the BPM value is displayed, you can change it with the Encoder!
To Eventide: I would suggest implementing this feature for the use with an aux switch. Tapping in the tempo while not in Play mode works perfectly, but the one tap – show BPM feature only works in Play mode and ONLY when you use the tap switch on the unit itself.