We had a great stay in the hotel (2 adults, 2 kids, 2 nights). Our room was bright and clean, and surprisingly spacious. Upon arrival, we noted that we were expecting an extra bed in our room; one was promptly sent up and made up. Breakfast was excellent.
The hotel is 3-stars for a reason: it hasn't been refurbished in a long time, so if you're looking for examples of cutting edge design, you might try somewhere else (probably outside of Eastbourne?). But The Lansdowne is very well looked after by the staff, and this gives the hotel a lovely nostalgic feel. Whenever we're headed to Eastbourne again we'll try to stay there first.