The Smart Siddur gives you the Prayers of each day.
For Example, on Rosh Hodesh it displays Yaleh Ve'yavo and Halel, while on regular days it doesn't.
In addition, it has a great user interface, and it's the most easy to use Siddur application in the market

***Tfilot included***
Shacharit
Mincha
Arvit
Birkat HaMazon

***Days included***
Rosh Hodesh, Passover, Sukot
Fasts
Tisha Bov (Including Eicha and Kinot)
Hanuka
10 Days between Rosh HaShana and Yom HaKipurim
Lag BaOmer songs

***More Options - Pro version only***
Smart silent mode
Pasuk before Yihyu LeRatzon
Prayer for the sick
Hebrew Month View
Zmanim

Hebrew fonts are installed. Although Nikud may be a little tricky, due to Android devices incompatibility.