Hardware-wise, there's no question it's a quantum leap over its predecessor. The Open C's dual-core processor makes a night-and-day difference in how quickly web pages load, and thus how the entire OS feels -- you're no longer left twiddling your thumbs. That extends to 3G data, too. It's both faster (download speeds hovered around 6 Mbps on Telus' network) and far more stable. The 4-inch, 800 x 480 display is much easier on the eyes than its smaller, low-resolution ancestor, and even the plastic casing is decidedly nicer to hold. About the only disappointment in the Open C's hardware is the 3-megapixel fixed-focus camera, which remains as consistently terrible as the 2MP shooter on the first Open.
The software is where it gets complicated. There's no doubt the OS has grown up in the past year. Besides adding those hoped-for email alerts, it now has a lot of features that made a difference in my day-to-day usage: music control from the lock screen, better graphics technology (you can play Cut the Rope!) and a timer in the clock app. I also liked that Firefox can now organize searches into smart collections that keep things focused; if you want to look for sports-focused web apps, you don't have to wade through unrelated services. As a rule, there were considerably fewer show-stopping "I can't do that" moments than the last time around, and I was happy to rely on the Open C for basic tasks.
Of course, I still ran into plenty of challenges when trying to accomplish more than the fundamentals. Simply put, the app ecosystem and feature set aren't where they need to be. I still couldn't get mainstays like Instagram, Rdio or Vine, and equivalents to major apps are either tough to find or not as powerful as the real deal. I found a decent Foursquare substitute (Around), for instance, but it's not going to rival the abilities of an official app like Swarm. Big-name social sites like Facebook and Twitter also don't integrate with Firefox OS, so there was no way to check for updates without launching associated apps. I had little choice but to carry another smartphone to fill feature gaps, whether they involved tracking Twitter mentions, obtaining turn-by-turn directions or just playing sophisticated games.
As such, the Open C can't serve as my only phone, at least not in its current state. It's really a refinement of what I saw in 2013: this is a superb device for its target market of first-time smartphone users in developing regions, but I'd have a hard time recommending it to American or European friends who have plenty of viable alternatives. When the Lumia 520 (which often sells for $59 or less) and Moto E ($129) have both more sophisticated platforms and occasionally better hardware, ZTE's $100 unlocked phone doesn't seem like such a bargain. More powerful Firefox phones are coming; the OS either already has or will soon get support for more advanced cameras, NFC pairing and fast LTE data. However, Mozilla absolutely has to work overtime on bolstering software support if it wants to court veterans like me... and, for that matter, to stop people from flocking to ever-cheaper Android gear.