Trade like domestic stocks on U.S.-listed or U.S. OTC exchanges during exchange hours and are priced and settled in U.S. dollars.

Listed ADRs must file quarterly with the U.S. Securities and Exchange Commission (SEC), providing potentially more information for researching a stock.

Some ADRs are marginable and have listed options trading.

Local market securities tend to be more liquid with narrower spreads, potentially offering better executions than the U.S. OTC market. 

Foreign companies not available as ADRs or foreign ordinaries on the U.S. OTC market can often be bought on local foreign markets.

Less liquid and more volatile compared to foreign stock shares traded on local market exchanges.

ADRs have custody pass-through fees that are levied on a regular basis (e.g., quarterly or annually.) You can search for individual prospectuses online using the U.S. Securities and Exchange Commission's EDGAR Company Search.

OTC markets are subject to fewer regulations and reporting requirements.

Not every foreign company has an ADR or Foreign Ordinary traded OTC available for U.S. investors.

See all the drawbacks here.

Subject to the foreign exchange market's hours, and stocks are priced and settled in the local currency.

Some countries impose controls on foreign investing that can limit a U.S. investor's equity holdings, require them to place trades in round lots (standard trading amounts) and/or delay their currency conversions. 

Foreign countries can have different tax treatment than the U.S. and may also impose additional fees or taxation on U.S. investors.

Foreign exchanges can limit equity holdings for U.S. investors.

Foreign exchange regulations can differ from U.S. laws which can make researching a stock more difficult.