In practice it works reasonably well. I have been using a BK 10Mhz analog function generator for the past several years and this device is a step forward and significantly lower price. (~$60 delivered from ebay)
It has the requisite knobs to adjust frequency, DC offset and Amplitude, and push buttons to select the decade, waveform and setup the sweep parameters. The LCD makes it much more intuitive to set up a sweep pattern then the old BK.
The downfall of the old BK was the massive drift associated with waveforms. This DDS seems to have a consistent 20ns jitter which is acceptable in the environment in which I use it.
The UD-B could definitely replace the BK function generators that we are using the in the freshman labs at a fraction of the cost.