I'm the opposite chino.. lol
Here something I posted in another thread in this forum (it's on the first page) discussing how speed affects gameplay. I'll just be lazy and copy/paste my thoughts on that subject.
To each their own when it comes to the speed option in gameplay, but I think this should stay bumped for a bit, because "speed" does affect gameplay on the field, with most or all players, in my opinion. Like I've already stated, I use normal speed and that is good enough for me, and I enjoy it much more over slow.
One of my main things is having the game play at speed that I feel is somewhat close to the pace of the NFL players moving on the actual field, and normal is just enough for me. After playing slow in this year's version, it is just too sluggish. You still see all the great animations on normal speed as well. I also find the running game for both the user and CPU is better on normal. You have to be more patient than on slow, while everything is moving at a quicker pace, and you also have to set up your blocks with correct timing a little more carefully. It, in my opinion, is just a more reward experience running well on normal speed. Running on normal feels better to me, overall.
Plus, I like the challenge (over slow) of having to read through my progressions a little quicker, and definitely having to make O-line pre-snap adjustments first, before calling the play, if I see pressure coming. Otherwise, a lot of the time you either don't have time to throw or get sacked.
EDIT: By the way, I played solely on slow in M25 and preferred that much more over normal speed, but that's just not the case for me this year. Another thing I notice on slow speed, the holes that open up in the middle stay open and don't close as quickly (as they do on normal), allowing gashing runs up the middle, much easier than the quicker pace on normal speed. Though, you also have to factor in how well your O-line is compared to their D-line (player ratings).