The wide receiver joined the NFC West side from the Minnesota Vikings as part of an off-season trade last year, but he missed the majority of the regular season with a hip injury.
The 25-year-old told NFL Network: "Man, it's been weird, it's been frustrating, it's been all the above, man. I had a tough time, and it weared on me a little bit, but like I told the others, my teammates have been A-plus-plus-plus. This whole organisation has been top of the line.
"You know, we already have three, four good receivers. I'm just adding to the mix. We just think with all of us collectively on the field together along with trying to stop the Beast Mode, we just feel it will be a tough time for the defense."
Harvin is available to play in this weekend's Super Bowl after recovering from a concussion, which he sustained in the divisional round of the playoffs.