What are pros and cons of txindex option?
If you're using Bitcoin Core just for your own personal use, you probably don't need the -txindex=1 option. But, if you're using Bitcoin core for development or blockchain analysis of some sort, you will need to set -txindex=1 to be able to get transactions data for any transaction in the blockchain. 

The tradeoff is just that keeping an index is slightly slower, but allows you to do things like:

bitcoin-cli getrawtransaction aec2729f5e46750b310b6feadcf853098aa86df74f93322a701c29cd68b22568 


(where aec2729f5e46750b310b6feadcf853098aa86df74f93322a701c29cd68b22568 is the ID of a transaction that does not affect your wallet at all).

Also, if you have been running your client for a while but haven't had txindex=1 set, then it might take a few hours to build the index. If you want to rebuild, launch with the -reindex option.