I stayed at this property last month and used the gym and pool.

The gym is small but good, has nice new equipment (I forgot the brand) and good selection of weight (however, in the lighter range only as I recall it). The gym is more than adequate for a hotel gym. I used it twice and I was the only person there both times, so not crowded at all. If you need a bigger gym with a better selection of equipment I would recommend to buy access to one of the many gyms on Sukhumvit Rd.

The pool at DT is small but OK for relax/cool down; you will not be able to do laps. I like the pool area (new/stylish, green plants, new sun beds, proximity to the bar area and gym etc)

I didn't use the Hilton facilities so can not compare.