We spent 3 nights here in a room with no cleaning, which worked out fine as they'll replenish your towels every day and take out the trash, which is all you probably need for a short stay. The room was smallish but perfectly adequate and staff was friendly and helpful. The on-site onsen is heavenly and perfect after a long day. The free ramen was surprisingly good and we liked having all the coffee we wanted for free, too. Breakfast, was 800 yen, as I recall, and a good value with a decent selection of western and Japanese food.
It's about a 10-minute walk from the streetcar and many good restaurants nearby.
The castle was quite impressive, as were the gardens - both of which made Takamatsu a good stop on our sightseeing travels.