It's basically a straight continuation of the first season, but Keima gradually discovers more background about the 'Lost Souls' he and Elsie have to collect. (Most of this information comes from Haqua, the classmate Elsie looks up to but who doesn't perform well out in the field.) Not much out of the ordinary happens -- though the episodes where Keima coaches a girl in his class to win the heart of a boy she fancies is pretty amusing.
There are a few 'side-episodes' (mainly for Keima to spout some knowledge about the games he is an expert in) but other than that, it's just par for the course. The last episode is quite bizarre though -- it's like the creators just gave up on doing anything coherent with the series anymore, because everyone lost interest. I guess there won't be a third season, and I'm fine with that.
- Opening and closing songs are quite neat!
- More background is revealed...
- ...but it's not needed as the series shuts itself down towards the end.
- Not that interesting anymore.
I'll give it a 6. If you're a huge fan of the franchise, you'll like it -- but otherwise you'll get kinda bored towards the end.