If you'be been following the field, you are probably aware of the recent (10/20/2014) joint statement from the scientific community, which concludes: "We object to the claim that brain games offer consumers a scientifically grounded avenue to reduce or reverse cognitive decline when there is no compelling scientific evidence to date that they do."
End of story? The picture is more complex. The ongoing scientific debate is summarized in this recent article in Cerebrum.
If you are a young adult, with satisfactory cognitive capacity, most "brain games" on the market today are unlikely to provide you with significant benefit. If you are over 40, or suffer from some form of cognitive infirmity, research shows more promise (see recent NIH-funded trial).
Best bet: try (dual) n-back training for working memory and attention. The exercise requires a higher level of focus and concentration than the typical Lumosity game: HighIQPro (commercial, $20-$50). Brain Workshop (open source).
SharpBrains, the market research firm which tracks "health and performace applications of neuroscience" provides ongoing, high quality coverage of the industry.