A deck can't do well without a stable manabase, so I hope the feedback I provide here can go a long way towards helping players to craft a solid foundation.
1. Present the mana curve in a line/bar graph rather a pie chart - I feel that it's easier to visualize a deck's curve if it's prominent. A pie chart fails to adequately present the curve IMO.
2. Show a deck's color distribution - now this can be presented using a pie chart. A simple weightage by mana symbols should suffice.
3. Introduce Baxter analysis - I believe this is a very sound yet underappreciated concept. Grasping this should help a player come up with a better idea of the proportion of mana lands to utility lands, just to name a benefit.
I haven't rated this app yet but good work so far. I'll be expecting much more from you from now on :-)
Very valuable insight, thanks for introducing me to Baxter.
On point 1, I somewhat disagree - I think it's just how most people got used to the bar graph, rather than it being 'better'. Nevertheless, I'll add it eventually.
Point 2 is kind of already there, albeit you have to look very carefully, as some of the users noticed a few days ago ;)
http://imtgapp.com/forum/index.php/topic,195.msg752.html#msg752