It depends on what you want it for.
When the OP-1 came out, iPads were expensive, flawed and had little software, quirky gadgets were not quite as trendy - maybe some devices appeared, but the OP-1 was very unique - and it was also somewhat cheaper than it is now, for relatively more processing power compared to other DSP-based synths and costs.
It was, in essence, a handful of quirky DSP synths running - by design requirements of the processing power available - at relatively low resolutions and ‘depth’ of output, in a neat and beautifully made box, with some clever recording tricks.
If you think of each synth as an individual ‘toy’ instrument, they were under $100 each. When sub-$100 meant Korg Monotron (TE have even redefined what a sub-$100 electronic music toy is). They were all in a single box with a mixer and speaker and sequencer all built in.
It was, in essence, absolute bloody genius, and absolutely good value. Like a portable, usable Plugiator - a box which was cheap, nasty, flawed and about £400 (IIRC) before you’d filled it with extra plugins, and had no recording or control within itself (it started out as a daughterboard for CME’s higher-end controllers).
In the 8 years since, processing power and programming skill has improved. Higher resolution, greater audio dynamic range, clearer harmonics, greater stability, much more storage are all possible. Devices like Deluge show the way, devices like Circuit show how to do cheap, multifunctional and playable with decent audio quality too.
No-one has matched TE’s industrial design, workflow or UX. But everyone has surpassed the actual audio quality of the instruments. So for your $1400 you could buy a bunch of interesting synths like the Model D, MS-101, MicroMonsta, Ambika… so many options now, run a free sequencer or Cubasis on iPad. Or you can pick up an iPad and Korg Gadget and it will, honestly, vastly exceed anything you can create with an OP-1. It’s a different experience, but the quality of the output, the sounds and audio, will be better.
Where the OP-1 should be now, is running with more processing power simply to allow, say, a drum pattern to play while you noodle on a synth - no need for tape. For $1400 it shouldn’t sound so thin in a mix, so insubstantial. A virtue was made out of the compromises needed to achieve what they wanted, and people went for it, but 8 years on, it’s time to let the OP-1 become a true version 2.0. Don’t mess with the good stuff - it’s like an original Apple Mac 512 to me; and we made whole magazines on that 9" screen, but damn it - the OP-1 should be an SE/30 by now.