I wouldn't have minded the turret sections so much, but a few of them felt so out of place. Take the one on the Geth tank: you can't do *any* damage to the reaper whatsoever and it only lasts like 20 seconds. It's only purpose was to convey an moment of epic scale as you're trying to outrun the thing.
Then there's that one mid-way through the London interlude section...I mean, why?! You're going through a series of heartfelt last goodbyes to your crew...and they slap a pointless turret sequence where you shoot a few waves of husks smack in the middle of them. Talk about spoiling the mood!