1. Security. Wi-Fi devices in ad hoc mode offer minimal security against unwanted incoming connections. For example, ad hoc devices cannot disable SSID broadcast like infrastructure mode devices can. Attackers generally will have little difficulty connecting to your ad hoc device if they get within signal range.
2. Signal strength monitoring. The normal operating system software indications seen when connected in infrastructure mode are unavailable in ad hoc mode. Without the ability to monitor the strength of signals, maintaining a stable connection can be difficult, especially when the ad hoc devices change their positions.
3. Speed. Ad hoc mode ofen runs slower than infrastructure mode. Specifically, Wi-Fi networking standards like 802.11g) require only that ad hoc mode communication supports 11 Mbps connection speeds: Wi-Fi devices supporting 54 Mbps or higher in infrastructure mode will drop back to a maximum of 11 Mbps when changed to ad hoc mode.