Increasing the number of partitions or subpartitions reduces the number of rows per partition, so queries which go in on a partition will have less work to do, also partition based operations may be quicker. However the maintanence of partitions may become more time consuming and thus take more of your time.
Partitions can be very useful indeed but you should fully understand all the possible options with partitioning and do testing to find the best one for your particular app. Also consider what partioning maintanance jobs will have to be created. The concepts manual is especially useful.