I'm currently using Pennzoil Ultra Platinum 5w-40 in a '04 Odyssey with J35A4 engine that specs 5w-20. I did it this summer in an effort to combat oil consumption (with 5w-20, it'd use about 2.5 quarts in a 6-7k OCI); it's too early to tell yet if it's helped in that regard.
Since purchasing it at 130k miles (has about 175k now), I'd only used 0w/5w-20 and once or twice used Mobil1 0w-30 AFE. I really can't tell the difference between any of them, the engine runs the same and had always used about the same amount of oil regardless of what was used. The 5w-40 this time is a curiousity thing, to see if it might help. I feel like it may not rev as fast, perhaps not as responsive using the thicker oil, but the difference is minimal. This engine has VTEC and the thicker oil has made no difference with the VTEC solenoid that activates the second cam profile.