Not everyone's taste but this is just how I love our Kawada Mami.
For a series full of characters I can see why it's hard making an appropriate OP if they want to emphasize on all (or most) characters at least a bit. The OP itself isn't too impressive but there
are notable good points about it. For instance I see there's a nice contrast from how the background (mostly Academy City) is quite pale, but the characters being 'colourful' makes it more dynamic. The action scenes at the end are nice but Vent vs Touma came a bit short and it's funny how Accelerator's crazy faces are emphasized upon (not saying it in a bad or good way).