Personally, I think it's crap.

It's overly aggressive, and clearly intended to lead users away from the legitimate, free option:

1) The BIG, BLUE SIGN-UP BUTTONS for the paid options, contrasted with the tiny, normal-text sign-up link for the free option.
2) Defaulting the ostensibly free option to a "donation" amount
3) The guilt-trip associated with a frown emoticon presented if the user - who has every right to do so - moves the slider to a $0 donation.

No other non-Automattic Plugin developer would be allowed to host a Plugin in the Repository if it did anything remotely like this. Akismet is bundled with core - an egregious issue that should be rectified by the release of WordPress 3.2.