That chess programs are strong tacticians is generally known. But the so called 'brute force' strategies and 'null move' technique are leading nowhere. Chess is not merely a game of calculating. Knowledge is getting more and more important, because it doesn't matter if a program sees a tactical shot in 2 seconds or in 30 seconds. Rebel 9 has a lot of knowledge, because of which it is able to play strongly in many types of positions.
Fast calculators are helpless in closed positions, in which they move their pieces like zombies.
In Computer Schach und Spiele, the leading German chess computer magazine, it was confirmed that Rebel is a tough opponent for all chess programs, simply because it plays all types of positions well. In general I would describe the playing style of Rebel dynamic, aggressive, positionally sound, with a good feeling of piece-activity and king's attacks. Maybe a surprising aspect to mention. But when I compare the evaluation of positions by Rebel 9 with other programs, I come to the conclusion that Rebel has by far the most reliable evaluation. There is a tendency in other programs to overestimate aspects like weak pawns, activity of the pieces, space.