I like the user interface, which is quite close to the Swipe UI on the N9. On demo videos UI is running quite nicely, even though the device is cheap and probably quite low-end specs. My understanding is that making modern UI running nicely Nokia ditched S40 platform and developed a new one based on the SmartedPhone OS. To me this makes the Asha 501 one of the most ambitious devices Nokia has developed recently.
I'm happy to see Nokia innovate again and that they had the guts to actually ship. Battle agains cheap droid manufacturers will be hard. For true innovators sake I really hope Asha platform will succeed.
Nokia's challenge is to make consumers understand the benefits of having platform optimized for low-end devices. The problem is that on paper these cheap Android devices look good, too good to be true if fact. And in real life most of the time they aren't good at all. Their battery life sucks, they are buggy, despite seemingly nice specs the UI can be laggy, and they are quite complex to operate. Some devices are obviously better than others, but in general at least usability, durability, and battery life should be clearly better in Asha 501. I'd also expect basic phone functions (calling, texting, etc.) to be way better in Asha given Nokia's years of experience in building mobile phones.
I think there are two markets for these new Ashas. Developing world is the obvious one. The second one is people in western world that want some smartphone features, but do not want complex device. I think iPhone has a lot of users that prefer it over Android just because its simpler to operate. Now, with modern UI Asha is way cheaper alternative and should be just as usable. For example I think I could recommend Asha 501 for my retired parents, or I might buy one for myself as backup phone for travel, etc.
As an application developer, I'm not that interested in the platform. I'm generally ok with Java as language, but I do not like traditional UI Frameworks and as long as there is no proper declarative way (like QML) of building the UI, I'm not going to bother. Good interface building tool might help here, for example Apple's interface builder is quite nice. I haven't actually checked if there exists one nowadays for J2ME, but I doubt it. As an alternative to J2ME it is possible to write Web Apps for Asha platform. These devices are having quite limited performance and with web technologies its even more difficult to write well performing apps so I'm not really interested in trying that route either.
It has been a while from the last time I was as exited about Nokia product as I am now. Glad to see old colleagues still delivering cool stuff.