Overall there was really nothing to complain of about the hotel, but just don't expect the same level of 'luxury' that you might be accustomed to if you've put up in more international 5-star hotels. The rooms and facilities at the Grand Hi-Lai are very comfortable and elegant, but the style and impression is traditional and decor seems almost dated, although everything is of course very well maintained.
The hotel's breakfast buffet offers a very generous and good quality spread across different cuisines like Taiwanese, Japanese, South East Asian and Western, although you can expect the cooking style to incline more towards the Asian palate. The only criticism is that the environment of the restaurant where breakfast is served seems almost a little cafeteria-like: it was extremely crowded and noisy with lots of tourist groups packed into a huge area. Nonetheless the service provided by the restaurant staff remained highly efficient and organized.
We had free WiFi included in our room booking for up to 3 devices, but I understand not every room deal is the same so just be sure to check this out before you make your booking if you need to stay connected while in Kaohsiung. I went down to the swimming pool, which was pretty average and even on the small side for a hotel. You should note that hotel policy requires all guests to wear a swimming cap if they wish to enter the pool, so you have to either bring your own swim cap with you, OR rent one from the hotel for around 3USD or buy one from the hotel for around 5USD (approximate price that I vaguely remember).
The location of the Grand Hi-Lai is fairly convenient: a pleasant 15 minute walk in the evenings down to the city's 'Love River', and lots of cafes and shops on the street outside the hotel. It's easy and inexpensive to catch a taxi to other parts of the city: a taxi ride to the Liu He night market costs 100TWD, and to the high speed rail station just over 200TWD. All the rooms are also on high floors, so you get very nice panoramic views of the city and the river both day and night. Overall it was a very comfortable and enjoyable stay with excellent service, just that there was nothing really "WOW" about the experience!