I think it depends on how well the guests know eachother. If they don't know eachother well then conversations can become strained, which will make for an uncomfortable atmosphere. Or you could end up with divided pockets of people who do know each other with some people being left out.
In that case some sort of activity is good for getting everyone connected and involved. I think most people's problem with shower games is that they are old and corny.
If people don't know eachother, icebreakers are a good in any situation and they can be tailored to fit the 'guest of honor'. So you could go around and have everyone tell how long they've known the New Mom, how they met and a character trait she has that they think will make her a good mom. (You could probably find a better icebreaker... but you get the idea).
If you decide to use games the trick is finding new, unusual games and/or activities. Some of the activities I've seen at baby showers that were fun were these:
* a belly dancer (yes! it was a backyard party and she was more of background entertainment as people ate)
* a blessing jar... everyone wrote down a blessing for the baby on small scraps of paper which were put into a decorated vase and given to the mom at the end of the shower.
* decorating onesies. There were onesies of all sizes and lots of different fabric paint and fabric pens - everyone stood around the table and decorated them. People got really creative. This takes up a lot of time.
* at the same shower the only 'game' they had was played throughout the shower: everyone got a necklace made from ribbon with a tiny plastic pacifier tied to it. During the shower if someone caught someone else using the word 'baby' they could take their necklace, at the end of the party whoever had the most necklaces won some sort of prize.
Sheesh, if you did each of these (belly dancer optional), with food and opening gifts you wouldn't have time for games.