I’ve seen both reverence and irreverence at the funeral Masses I’ve attended.
What I don’t like much during viewings prior to the Mass (for an hour to two hours) is when the family of the deceased sits in the front two rows, and everyone else goes up to hug them and socialize, oblivious to the fact their backs are to the Blessed Sacrament. They continue socializing in the pews before Mass. It’s usually the more devoutly-Catholic family members who stand at the back of the church to accept hugs and condolences during this time, and they do a better job of subduing their voices.
At a recent funeral I attended, several people gave their “eulogies” prior to the Mass – including the Catholic live-in girlfriend of the deceased, who shared about many details about “the good times” they shared and how she and her daughter were going to miss him. The celebrant didn’t attend this part – I don’t even know if he knew about the co-habitating, but during his homily he talked about this man’s being in heaven now.
My stomach was tied in knots one time – several law enforcement officers clomped into the church with their guns during the viewing. A few got up to leave a few minutes after Mass began. I don’t even know if any churches have policies re: guns in the church, but it was upsetting.
Most priests make some statement re: who can receive Holy Communion during funeral Masses now, it seems, but I still see non-Catholics, and non-practicing Catholics, defy this and receive.
I think for the most part, we see a degree of seriousness during funeral Masses because of the occasion, but not necessarily more “solemnless” than during a Sunday Mass. I have actually been told by a few people that they attend for the deceased and his/her family out of obligation rather than an intention to worship. But I believe that no matter what the intentions may be, God, who works in mysterious ways, works in their hearts anyway.