Don't do it! It's a trap!

I always feel sentimental about my exs. it's always when they're gone that you think about the good times or you smile when they talk - I mean, you were attracted to them at some point, right? The sadness and bad things only manifest later when you're more settled.

remember the reasons you broke up still probably exist,

then do what feels right, I guess. I almost got back together when an ex, but I realized that we were really just not suited to each other right now. But at least I had a model of what I like in my mind because of him.

I never date that model, but at least I know.

....What Gil said....

It could be that the grass is greener on the other side of the fence- it seems like it'd be better being back with her, but you're overlooking all the things that made you split up in the first place.

If you think about those things and you reckon you can handle them better now than you did then (ie. you won't want to split up again), maybe it's worth trying again, otherwise it might be worth exploring the "Just Good Friends" route (as long as you could bear the idea of that)...

I might have stated the obvious there, but sometimes the obvious needs to be said, all the same.