Great bit of kit, tons of inspiration but a couple of minor issues...
Build is good for the price but one slightly wobbly encoder (#9), one pad needs a bit more of a bash to register than the rest (#16) and the grey trim on the left end panel sits slightly proud of the base leaving it prone to chipping off. Also, the scaling of the encoders in controller mode is great for fine control but takes several complete turns to go through the full range. This makes it less useful for filter sweeps etc.
All of these issues are outweighed by the sheer fun of using the device. The step sequencer in particular is the best bit of kit i have encountered for generating musical ideas. I'm really looking forward to using the Beatstep in the context of a live performance, it gives you the chance to make evolving sequences on the fly and in that respect beats a static arpeggiator hands down. If you've got and analogue synth, buy one. If you're bored of mousing things into a piano roll, buy one. The most (legal) fun you can have for less than £100!