Overall I was quite satisfied with my overnight stay.

I chose this hotel for its central location - on the waterside right across the marina. But it is rather far from the railway station. Those arriving from the airport with bus line C9A can get off at "Policarpo Sanz" and stroll downhill to the marina. However bear in mind that Vigo is built on a hill (steep streets!); I strongly recommend to have a city map to find your way.
Booked my room on AC Hoteles own website - I got an unbeatable "Winter Offer" discounted fare of 60EUR for a standard room excluding breakfast.

Check-in quick but the receptionist was a bit distant with only limited English skills. I was given a room on the 3rd floor with a nice front view over the marina. It was quite spacious and functional. Pleasantly surprised by the amenities: individual air-conditioning, large closet, individual safe, small working desk. The bed was comfortable with four pillows and a very firm mattress. All equipment working properly. Bathroom is small but adequate, bath and WC spotlessly clean.
A nice touch was the free minibar including diverse softdrinks, juice, mineral water and beer - but no snacks or chocolates.
I travelled off-season end of January, so that night life in Vigo was limited. The night club mentioned by previous reviewers was closed. However in busy summer, I guess that noise might be annoying.

On the downside the room service menu was limited and uninspiring. I also missed some coffee-making facilities.

I did not eat breakfast at the hotel, as there are many cafés and restaurants in the adjacent streets.

I had the distinct feeling that the hotel was understaffed, perhaps due to the off-season period. During my weekend stay there were only two receptionists on duty, the breakfast room had only one waiter and I did not see any maid. Both restaurant and lounge bar were closed on Saturday and Sunday!

All in all I can recommend this hotel for its central location, very comfortable room and good value-for-money. However travelling in January means very quiet evenings.