I went for the 3GS, I'd never used an iPhone before. A friend has the N95, and he says the iPhone is much better than his N95. The 3GS certainly has better battery life, you can buy external battery packs, I have an AA pack for when out on the bike. The camera is better than my Ericsson c902(5mp), reception seems to be just as good.
I went to a wedding at the weekend, was constantly checking/sending emails/wimbledon and I didn't have to charge my phone over the whole weekend, I was very impressed with the battery life of the 3GS.
I think you can get hold of Lotus iNotes for the iPhone, although I'm not too sure.
As said, its handy not having to take an mp3 player, phone, camera, when going for a ride. Even if you forgot your cycle computer, you can use the iPhone.
For me its also very handy being able to access the exchange server here at work from anywhere, and have my hotmail pushed to my iPhone.
Apps? There are sooo many, it will be hard for any other company to compete with the amount of apps. Well for at least another year.