Do you have the 9780 or know anyone who does? I'm interested in the phone purely because it has a bit of beef behind the screen and it has BIS included.
Yeah, I got a 9870 for about 5 days now (still in the honeymoon period, so im going to be biased towards it

). I NEVER thought i will ever get a BB, but I played around with a 9800 & thought that its not too bad(didnt like the form factor of the 9800)
Looked at the 9870 & loved it. I needed a phone with a good camera & the 5mp camera on the 9870 is actually very good. I was waiting for the SE Arc but i realised that data charges will kill me(as with any other Android phone). I mostly use my phone for internet access & since BIS is included I went for the BB.
As Crowley said, its really smooth, not one lockup, & the new OS6 looks really sleek. I was worried about the 'small' screen at first, but its well optimised & u never really feel it. The quality of the screen is really good, check the vidoe clip that comes with the phone - it looks like HD
The battery life is not too bad, gets killed in about 1,5 days. I still need to optimise things like e-mail, facebook, twitter etc to get more out of the battery. I know people who are getting 3 or 4 days per charge, so im not too concerned. Also any battery improves after a few charges.
The best thing ever is BIS, cos I really dont need to worry about being raped (R2/mb)
The new deals should be out today for MTN, check if the price has come down.