seremify007 gave probably the best view on BlackBerrys you'll get.
As a WP7/8 user (I had a Nokia Lumia 800) I'll give you my spin on it.
Nokia's physical handsets are actually really nice, the buttons are responsive, the screens are high resolution and are sturdy as all hell ie. dropping from pocket, etc.
They also come with a case in the box which is really nice as it matches perfectly and doesn't add too much thickness
Calling and messaging quality is the same as any other phone. It links really will with Facebook creating a FBMessenger experience inside the native messaging app which was a nice surprise.
Having had an iPhone previously, data speed isn't near 4G but its bearable (for me at least) but I guess that varies depending on how reliant you are on mobile data.
The Carl Zeiss camera is functional and you do get the odd good shot but it falls short of cameras on the iPhone/other high end smartphones as the images generally turn out grainy.
The app store is limited, being new on the scene the depth in the market is lacking. Admittedly, you will be able to find an equivalent for basically any app you want (Sidenote: As of the time I stopped using my Lumia there was no Instagram or if your big into mobile gaming WPOS is a definite no-no)
Facebook is pretty mediocre. The 'official' Facebook app (or at least Microsoft's version) is just a link to the Facebook website. Other apps give a slightly better experience but it's still clunky and generally pretty average.
One good thing about the WPOS is it gives you a bit more freedom as far as customisability is concerned. The ability to change the colour scheme and re-size apps is nice.
I think IGN or some place like that described WPOS really well "WPOS was never striving to beat Android or Apple, the goal was to settle in third, an alternative, yet mainstream enough to gain developer support"
Would I recommend a WP to anyone?
Depends. If you are after a phone that has all your favourite apps on it (Google Chrome, Instagram, games, etc.) your most likely going to be disappointed.
If you want a phone that text, call, FB, do the random internet search and is happy for a generic version of an app then sure.
A phone OS that is different from Apple and Android, WP is probably your best bet.
Acronyms:
FB = Facebook
WPOS = Windows Phone Operating System
WP (7/8) = Windows Phone (7 or 8)
OS = Operating System
PS; I'm selling my Blue Nokia Lumia 800 16GB for $175 (neg.) if anyone wants it.