I always disliked the character of Andrew as I found it slightly homophobic in how everything about him was played for laughs. He was the guy who when the heroes were out fighting was hiding at home in his pinny and rubber gloves washing dishes. His obvious crushes on Warren/ Xander/ Spike were always used for cheap giggles. There was none of the respect that Willow/Tara got. They had character outside of their sexuality and their romantic life was always treated as seriously as any of the straight characters. So to be honest I find it slightly disturbing that a gay actor would so willingly contribute to such a stereotypical character.
(Not to say anything about the fact that the first chance the Angel writers got they turned him straight.)
Andrew was a weak character no matter his preferences. To me, he was JW's version of Gollum, albeit one who survived when he maybe should not have. Xander's last comment about Anya can be seen as being far more snide towards Andrew than her. His devotion to the heartless Warren was sad, whether in friendship or love, and he killed the only person who could stand to be around him (ala Smeagle's cousin). If TL had been directed to speak in a less stereotypical way (my brother had to point him out in Transformers) Andrew might have worked better. Everything in BTVS S7 was more than slightly overdone, in MO.
Andrew was the next generation of Xander, despite whatever his sexuality was. Xander had grown up and his humor was becoming more jaded due to his experances. Andrew replaced that, by bringing back whimsy to the show in a season that most needed it. Xander couldn't even cry for Anya upon her death, while Andrew did.