I have used both the gue ins and clip ins. I bought the clip ins from ebay and I love them :o)
The glue ins were good but as i went quite a bit longer i got fed up of having to do something with it every morning, took me so much longer to get ready for work. couldn't tie my hair back easily because the glue shows through :o( obviously didn't have to worry about that with the clip ins. I used to use them alot to go out on the weekends and so they got swung round dancing and tugged on hugging friends etc. Also it meant I can die them the same as I die my hair so they'll last for a long time.
If you do go for clip ins and you have thick hair i would buy two packs, especially if you are going to wear your hair straight.
You can manage an up do with the clip ins too, i have mastered the art after a few times trying.
Also the need no management to look after, where as the bonds you have to be careful with when brushing, washing your hair.
I think i prefer the clip ins personally. Maybe buy some from ebay or somewhere and have a play, see what you think. If you dont like them get the bonds :o)