I find it a bit difficult to say where the Octatrack sits compared to other gear. In many respects, there is nothing like it. You're buying the workflow as well as hardware. However, that workflow comes at a somewhat steep, but not insurmountable learning curve, and you feel like you get faster as you learn it, because it is built around fairly practical key combinations, and if you spend any time with Elektron gear, you'll be happy to find that most of these things are universal among their gear, but I digress.
The Octatrack has a decent amount of memory compared to most hardware samplers (though I think in this day and age, they could do at least 512MB) and it doesn't have pressure sensitive pads like the MPC. However, if you are into hiphop or samples weaved into your electronic music of whatever genre and want to work with individual samples as well as slicing loops, it would provide a new take on the old MPC 16 pads I think the effects are pretty good. I like the P-locks. It is a quicker to work with the sample editor on the Octatrack than my Electribe ESX-1. It's also cheaper than a laptop+Maschine, and if you are really into sampling your own stuff, it might be better.
Here are my gripes.
Retrigger tied to the crossfader seems impressive in the demo videos, but IMHO, it gets old quick. It doesn't render the crossfader or retrigger useless, but I found pretty quickly that this was the most oversold feature IMHO. However, I guess I still like it better than Traktor retrigger and Turnado or Glitch retrigger. I just find that a little goes a long way. I find it works best with P-locks because you have more direct control over it, and it's repeatable. P-locks also work relative to the crossfader adjustments, so you get some interesting cross modulation if you do use it that way.
Saving samples is not that easy. I kind of wish they had provided a second USB port for a keyboard so you could type in sample names. I think there is a shortcut way to save everything, but I definitely don't look forward to playing librarian after the fact trying to give samples meaningful names, which would then break any project they were associated with. I prefer to sample with Ableton for organization reasons, but this is a same really, because the Octatrack has a pretty good sampling workflow. Just select a track, set the record settings (for which I wish there was a global default for fade-in, fade-out, etc.) and press and hold the button until you want to stop recording. The sample will be recorded into the recording buffer corresponding to the selected track. You can also make your own custom record pattern that grabs a sample every beat, plays it back, grabs another, plays it back, etc.
The MIDI sequencing is a bonus, but I've hardly used it. Mainly because I'm still used to sequencing in Ableton. It does have some limitations. You CAN control MIDI CC via knobs and the LFO, which is awesome, but I don't think it will receive MIDI CC and record it to P-Locks, nor does it have a MIDI learn feature, as far as I've seen.
Every sample must be assigned to a slot to be used. Not really a big quibble. Yes, you could theoretically use this entire thing to do a straight up digital DJ gig, but you'd want to get in a habit of preloading your tracks into the slots.