The PB is a no-brainer if you have a BB handset. For those (the majority) who do not, it's a tougher call.
The overall physical feel is, IMO, superior to the Fire. Minor point, I know, but that's my impression.
I like the OS quite a bit. Navigation is very fluid and intuitive once you get used to it. Multitasking is definitely a strength.
The OS2 update adds functionality that should have existed all along (native email and calendar, and file browser for example), and some new features that may take some time to mature (e.g. the Android apps, which still need to be validated before being available in the app store).
For media consumption, YT is fine. Hulu is still a no-go, and I do not use NetFlix.
For email, even before the new OS, gmail was decent-- loads better now, though. For work-related email access, the PB is very capable, as it should be considering its target audience.
As for apps, they are sparse, but there are some very good tools. An RDP app was recently released that is absolutely exceptional. There is also a nifty HTPC app that works perfectly. For most of my needs, there isn't a great deal of selection, but the few apps that are available do the job --most of the time-- and do it very, very well. YMMV.
Browser performance and stability have been much improved since the beta 2.0. However, I still cannot view .ogg HTML5 video properly, and I need to test the stability of 11n connectivity. 11g is just fine.
In the 7" form-factor space, and at the $200 price point, the PB is still a solid purchase even for non-BB handset users, IMO. I just came back from a trip, and having free unlimited WAN connectivity via our BB handset, through the bridge browser, was incredibly convenient. The size is also very handy for quickly loading a PDF of a train schedule, map, etc. The latter is not unique to the PB by any means, of course.