I like them as mysterious people from beyond, but I guess they are the new drow.
Drow used to be a race that didn't even have a write-up, just a brief mention in the elf entry in the Monster Manual that described them as "rumored" and "legendary".
Then they showed up in the D module series. That was cool; a refreshing change from more orcs and goblins, and hooray, we're finally battling this sinister, secret, legendary evil.
Then they became the most popular villain... it seemed that every dungeon had an enclave of drow that were pulling the strings. Dragon lair? Surprise, the dragon is enchanted by the drow. Orc bandits? Surprise, the orcs are working for the drow. River Rat thieves' guild? Run by drow. Door-to-door hairbrush sales? Run by the drow.
Then, as we all know, Driz'zt happened (or is it Drizz't? D'r'i'z'z't?), and they became a popular PC race.
The same thing is happening with the gith. Were I wiser, I would realize that one cannot fight the forces of popularity, but In My Campaign they are true to their roots: remote and legendary, not tavern-hopping PCs.
Mysterious race from beyond is a very good choice when a player wishes to stand out from the others. A 'standard' race is 'common' and therefore not 'unique' so the 'mysterious outsider' type races become popular for the players who wish to stand out against the backdrop(or stand out amongst their peers).
I like the way Drow look. I also like that they are not nature-oriented yet long lived like the elves. I dislike emo-fluff and the 'you must be evil!' portions as a PC, so I usually come up with a rebellious Underdark Drow who hated the matriarchy and tends to do what he feels is 'right'. Not as goody as Drizz't.
Granted, I don't play Drow that often either, since in 3.5 they had a con penalty and +2 LA, and in 4th I do not have the required books.