In my mind an episodic title is a game series that has a story which spans several smaller episodes, most likely using similar assets and presentation style. The key benefits would be a shortened development time (with associated faster turnaround for each individual episode) and the fact that the story/game can be tweaked/modified with successive episodes based upon feedback from earlier episodes.
There is also a key benefit that the development costs/investment can be spread over the full series, providing the opportunity to derive revenue from each incremental release. The revenue generated by each episode can be used to fund development of the subsequent episodes.
I think the episodic development model fits the Minis platform perfectly, for all the reasons above. I believe that those are the kind of games that many Minis customers want.
If there is a downside, I guess that it would be that there is not likely to be any major improvements made to the game engine or presentation with each subsequent episode. This is generally OK as it will ensure that there is a consistent look, feel and gameplay experience across the entire series, however people have come to expect subsequent games to have improvements across the board (including the visuals, audio & gameplay).
To counter this issue, the game series will need careful marketing as an episodic gameplay experience, rather than a series of 'sequels' in the traditional sense. As long as each individual episode has a fast development/production turnaround, then I don't think people will mind. After all, customers don't mind that each episode within a given series of Star Trek looks the same, indeed it is expected. It's only when you transition between different series that you expect substantial upgrades to the presentation & content.