Limited seats available depending on which ferry you ride on. Not air-conditioned. Had to stand among the vehicles. Not an ideal service on rainy days. If you're riding Grab to the ferry terminal on the Georgetown side, you have to cross the overhead pedestrian bridge. No elevator/lift available. Not recommended for children/elderlies.
The trip took about 15-20 minutes. Free shuttle bus available to and from bus and train stations to the jetty on the Butterworth side. Recommended for solo travelers/backpackers. Low-cost option.