Since I found out about the pocket operators series, the one that I always wanted was a sampler, teenage made it so I bought it.
First of all, if you're looking for a sp 404 or a mpc for a fraction of the price, just forget about it, you're going to blow 100 bucks(its monophonic, 40 seconds of sampling time etc...).
This is a great machine, you can record through the built in microphone and then you can cut, pitch and throw a low/high pass filter to the sample. After that you can sequence all the sounds and you can chain sequences together in order to create a song or simply make a 16,32 etc step sequence.
Good: The effects are incredibly fun to use. After creating a sequence you can create a performance by using them.
Bad: the samples are divided in racks and you can't play a 2 samples from the same rack at the same time. For example, if you have in a drum rack a quick drum and a high hat, you can't play both at the same time, the last one added to the sequence will delete the previous sound in that step.
And the sequencer is 4 notes polyphonic, so when 4 samples are playing at the same time, if you add a 5th sample to the sequence in that step, one of the samples will stop playing. That can be a good or a bad thing, sometimes can mess up completely the sequence but other time can help to to create a dynamic sequence through out the time, by adding some samples, others fade away.
Other thing that might be upsetting: You can add samples to the sequence by 16 step mode or live mode. Even though its possible to record live to the sequence, what you play is quantized, so if you try to do something weird keep in mind that the sequencer can mess it up because will quantize what you play, regardless if you want it or not.
Conclusion: Is incredibly fun machine, if you use the limitation in your advantage, you can create really cool things with it.