Early reviews seem to indicate that BB10 is good and the phones are hardware competitive. I like the minimalist design of the Z10 a lot, and it seems that it would be comfortable to hold and use.
I think it's enough to keep Blackberry in the game for a while, but Flow and the BB keyboards aren't big enough draws. They could keep a significant portion of the enterprise users they still have left, but the new UI isn't going to sway Apple users and Android users. BB10 is more of a stopgap at this point than anything else.
Staying alive is all Blackberry needs to do right now, but it's disappointing that there aren't more compelling reasons to switch. In a month I will be getting a new phone, and if the Z10 is at least stable (my previous full touchscreen BB Storm keeps haunting my smartphone nightmares) there's a 50% chance I get one. Otherwise I'll likely stick with Windows Phone and probably get a HTC 8X. Windows Phone wasn't a big hit at launch, either, but Zune, Office, Skydrive and Xbox Live were appealing services/features. And if I don't see a reason to switch - and I'm an early adopter and as ecosystem-agnostic as anyone else - I can't see a significant number of smartphone users even considering it.
I know all the members here with a personal stake (read: stockholders) will wax eloquently about BB10 and the new phones, and I do want to be positive about Blackberry's future, but it seems like the next generation will the one to make or break Blackberry. I'm not that excited about what I've heard and seen so far. I do have to give RIM Blackberry for sticking with their plan, though, at least they've showed up even if it's a bit late.