I've done this before and would do it again.
PRO
- Much cheaper fare in Business and Economy
- Almost always 125% status miles in Business
- IMO good food, service, seats, AVOD, hard/soft product on board
- if TK J, ease of facilities/customs/etc. at IST
CON
- transit times of 2 - 18hrs (but I think gives free transit hotels?)
- IST can be chaotic is not *G or flying Business
This has often been the cheapest option I've seen, even factoring in the costs for an overnight hotel. There are worse places to transit that IST or places to overnight than Istanbul!