Choice Band Talonflame is the nightmare of Pokemon. Flare Blitz/BB hit just about everything in OU extremely hard 2HKO'ing just about everything. Here are some statements of it's power:
252+ Atk Choice Band Talonflame Brave Bird vs. 252 HP / 0 Def Mega Venusaur: 392-464 (107.6 - 127.4%) -- guaranteed OHKO
252+ Atk Choice Band Talonflame Brave Bird vs. 252 HP / 184+ Def Gliscor: 153-180 (43.2 - 50.8%) -- guaranteed 3HKO after Poison Heal
252+ Atk Choice Band Talonflame Brave Bird vs. 252 HP / 0 Def Sylveon: 334-394 (84.7 - 100%) -- 81.3% chance to OHKO after Stealth Rock
What Talonflame does in a nutshell is just spam Brave Birds until something that comes up walls it, or until it dies. All teams should be prepared for this thing, ripping through Mega Venusaur in one hit is not something you want to mess with. The best counter you can find are Stealth Rocks (duh), Azumarill or ScarfDrill are the best mons I can think of. Lets look at this for one second:
ScarfDrill outruns Talonflame's Flare Blitz, and can take a BB and OHKO back with Rock Slide.
252+ Atk Choice Band Talonflame Brave Bird vs. 4 HP / 0 Def Excadrill: 177-209 (48.8 - 57.7%) -- 96.1% chance to 2HKO
252+ Atk Mold Breaker Excadrill Rock Slide vs. 4 HP / 0 Def Talonflame: 492-580 (165.1 - 194.6%) -- guaranteed OHKO
I highly doubt this will increase Excadrill population though, Stealth Rocks is much safer and better, as Azumarill does not need to waste an important item slot to defeat Talonflame.
Back onto Topic, we all already know that Talonflame is stupidly powerful, but it's main downfall is it's attack. Having only slighly over 80 is BAD in this Meta-Game. Needing Choice Band or a Swords Dance up to do real damage is not something a Pokemon would want in this tier. Any pokemon that can outspeed and resist/live a BB usually can destroy TFlame's dreams. Overall, Talonflame gets a 8/10, just because of it's downright bad attack.