I had the misfortune of trying to connect through MSP today departing from SEA. I was originally booked on NW158. Once it was delayed (mechanical) until at least 1PM, I switched (along with many others) to NW170 departing at 12:15PM. Then we experienced another delay (mechanical) that forced us back to the gate. The GA came on and said that there would be tight connections and that planes would be held if the time was close, but from the looks of the tickets being reissued at the gate, it didn't look to be the case. We were about 15 minutes later than the last predicted time. I missed my connection by 5 minutes (received the rebooking email) while taxiing.

All in all, NW and the employees handled the delays very professionally. Can't really complain (aside from being seven hours late), as I would rather be safe than sorry.