Sure, they're interesting to play, have their own unique strategies and all that jazz, but then so do all other RTS factions worth their salt.
But the Orks in WH40k ooze more personality than any other faction I've played in an RTS. From the unit names(Slugga Boyz, Shoota Boyz, Warboss, Wartrukk, Killa Kan), to the structures (Da Bigga Generator, Da Boyz Hut, Da Mek Shop),to their war cries, to the legendary Waaaaagh!, they are drop-dead funny and terrifying at the same time. Gotta love 'em.
In fact, WH40K is fast becoming my one of my favourite universes - I'm playing Dawn of War. I've already played Squad Command on the PSP and the strangely enjoyable Glory in Death for the now forgotten N-Gage. I'm planning on getting Mark of Chaos, and .of course, am eagerly awaiting DoW 2.
I'm also on the lookout for WH40k and Warhammer tabletop games and comics. To add to my prized collection of Hellbrandt Grimm graphic novels (Eat your heart out, koidy!)