@mycophile: you can get a dispenser reasonably cheap and it works so much better. It makes sucking on a whipped cream can seem a lot weaker.
I don't know how long you've been using nitrous, but I found that I like it more the more I use it, but at first it seemed like it got worse over time. Like there was a dip in the graph, if you will. I have no idea why that is, but maybe it's what you're experiencing.
I don't have a dispenser but about 2 months ago I bought a cracker and have been enjoying balloons with it ever since and yeah, it's much better than whip cream cans.
I don't know why everyone seems to prefer a dispenser to a cracker though, but at the moment I don't see the reason to spend the extra cash on one.