Although minimal, I did find that the ballpoint (P900) had some slight play while writing (really, not bad at all, but somewhat there), but the rollerball felt rock solid. Not sure if the refill size and shape differences made up where they contrasted, but something to note.
While writing the pen feels pretty balanced. Maybe a hair heavier towards the top, but is quite comfortable. The matte texture of the grip makes the pen less slick, but not "grippy".
The final point is regarding the stylus. I'll admit, I don't use a stylus personally so having one incorporated into the pen isn't a major selling point for me. But, I know there are a lot of people that do and having it may be a really convenient feature.