I used the Ferry for the 'Rail and Sail' package to Edinburgh for Hogmanay.
I travelled on the early morning service. The ship was clean, tidy and had plenty of different areas to explore. Unfortunately, a couple of things let the trip down. I queued for 25 minutes, to get breakfast in the cafe, there seemed to be a lot of staff working however they all appeared to be 'doing there own thing', there was no co-ordination amongst them. For example, they were serving one customer, going to get toast, and then waiting of the chef providing the food, rather than working the queue and serving the next customer whilst they were waiting. The food itself was tasty, albeit a little on the expensive side £8 for a sausage & egg bap and a drink. I was able to get a comfortable seat for the duration of the sailing,
The return journey was very packed, At the port the walkway was broke and we had to be transported to the ship via bus, which caused a lot of frustration amongst passengers, as there was a mad 'surge' to get a seat on the sailing when we got onboard. I managed to mind a comfortable little spot for myself on a bench! Some passengers were left to wander around during the crossing.
Arriving back in Belfast there was a 30 minute wait for the bag I checked in.
Cheap to travel
Allows feasibility of carrying large amounts of luggage
Onboard catering expensive
Possibility of slow service from catering staff
Might not get a seat.
Would I travel again? - Yes probably as long as I wasn't in a rush.