I have purchase nautilus 61 and i took my took my time to learn in death. This has meant to replace my Motif ES6. Not an easy task because to this day a ES6 18 years later its sold second hand at a bit than half the price of a Nautilus. I am a mostly ambient composer , that i focus a lot more on sound design than sequencing. So Nautilus with its 9 engines seemed a sae upgrade.
Summary: in short Nautilus is massively powerful and flexible synth severely limited by terrible hard snd software interface.
Pros: average sounds you will expect from a modern workstation , quite close to its competition. None of them will blow your mind away in uniques and complexity like a korg wavestate or the new poly can. Sequencer is very powerful and will please those coming from s linear DAW like cubase. The mpdulation options will blow your mind away toms to choose and a sophistication modulation that can add and multiply modulation results together.
Cons: horrible hardware interface. The keybed is excellent for synth action nicely weighted and responsive. No mpdulation wheel instead there is a joystic that is two pitch wheels on one. As such as soon as you leave your hand resets back to zero. Only 6 knobs with only custom assignment each. No fades , very few buttons , almost all of the with no secondary actions. 6 buttons are assignable but even those uave very limited options.The worst touch screen I ever used. Its failure rate on touches goes from 10% to 90%. I have operated worn out 20 year old ATM touch screens massively better than this crap.UI os terrible it completely lack easy screens to access most common parameters everything is hidden in the last place you will expect. Modulation is very powetful but make little sense and how its designed and being all over the place. Overall the worst menu diving i ever experienced in almost 30 years of working on hardware and software synths. UI is occasionally laggy , 1 to 2 seconds. The engines come with zero presets of their own. You can use up to 2 engines at the same time but can have individual presets. Your only alternative is combis which allow you to mix and match presets sounds but not engines. Combis come with downside of consuming tracks but are easier to layer and than individual engines. You cannot use the Rompler engine apart from itself calld HD1 , it only offers 2 layer of simultance sounds and another 6 for velocity splits. Engines sound good but not great limited from the low processing power , korg multi poly and wavestate completely destroy both Nautilus and Kronos in audio quality, unique presets, nostalgia and perfect anologue emulation.
Conclusion: if you look for s workstation that sounds great, easy to learn, super easy to use with excellent touch screen and brilliant ui that needs no external editor. Roland Fantom 06 is probably the best workstation ever created.