I actually think he was quite underrated in his day. He had a terrific forehand, on par with some top 15 players. Can hit it with great spin (worked really well on clay) but also flatten it out in a huge way. He actually gave Roger a couple of tough matches in majors. The 5 setter at the US Open (2008) is the one people remember most, but there was also a VERY tough 4 setter at the 2010 Australian Open.