The good news about Bento 2 is that it gives Leopard users access to their Address Book, Calendar and Tasks. Mail too, I think. That's probably worth $50 for me, especially if the current version FileMaker can't access these stores (I use an old version of FMP, haven't yet seen a good reason to upgrade.)
The bad news is the queries (called smart collections) can't be nested.
So you can define a query, but you can't reference it in a second query.
iTunes allows nested queries, I use them extensively. iPhoto doesn't, I miss 'em.
Some aspects of databases are hard to understand, but iTunes shows that regular users can learn to appreciate nested queries.
So, unfortunate omission.
I'm going to see if I can use Bento to help merge my Gmail and personal address books. If it works for that, I'll buy.
Even without the nested queries.
Update: I watched the videos. You create relationships by drag and dropping records. The 1 many relationship is seen through a "portal" window in a Bento form. Problem is, I don't see how you create a relationship by, say, relating all persons common last names in a single view. Bento would be more interesting if it were integrated with FileMaker, so we could use Bento to access iCal and similar stores but use FM to do more useful operations.
Update: There's no FileMaker Pro integration. The two are completely separate products using unrelated data stores (SQLite for Bento, as in /Users/account name/Application Support/Bento/bento.bentodb/Contents/Resources/Database). You can't link from a FileMaker Pro database into a Bento Library. Yuck. The only way out of this would be if someone figures out a way to use a more powerful SQLite app to manipulate Bento data. I'll watch for that.
This Nov 2007 Daring Fireball post has some more leads for understanding Bento.
Actual Technologies sells a connector that may allow a FMPro app to access SQLite data, may be read-only.
Bento is apple scriptable ...
Update 11/2/2008: Still in my trial period, I tried using Bento to enter several items quickly into my large iCal (several calendars, total 6,300 events). This is a trivial task with Outlook and its multiple views, but it's not supported in iCal.
Opening the Bento database, which includes the iCal tables, took minutes. Adding a single record took a minute. Type lag was severe.
Bento operations were excruciatingly slow on my single-core G5 iMac; manipulating my calendar reliably pegged the CPU. I was surprised how crude the UI was for specifying a calendar in a filtered view; I expected a drop down list but instead had to type the calendar name.
When doing data entry the type lag was gruesome. Yes, in a bloody database app there's type lag. It ain't doing fancy type layout, where the heck is the lag coming from?
When viewing a "collection" you can't create a new record. Lame.
This is an achingly inefficient load of software. It's miserable.