Dry and liquid extract each have their advantages and draw-backs.
What are the perceived ups and downs for using one or the other?
Because many extract brewers do a partial-wort boil the concentration of sugar increases the caramelization process, darkening wort faster. This applies to both liquid and dry malt extracts.
I like dry extracts over liquid for thier shelf life and ease of mearurements. THe draw back to dry is that the powder is really fine and can make a dusty mess of your counter top and scale during measuring if you are not careful.
Liquid extract tends to have a short half life and its more difficult to get it all out of the container it comes in unless you do some rinsing with warm water.
I do like the "preset" mineral profile you get from the brewer that prepared the extract, and when liquid is really fresh its great stuff. But finding really fresh extract tha comes out of a bulk container is tough in my neck of the woods.
I tend to use dry extract as my "oh shit I need more sugar" tool, and liquid as my normal extract recipe ingredient. Dry definitely has it's benefits of shelf life, assuming you take care of it. It has to be kept dry. A little moisture and it's pretty much shot.
Depending on your homebrew shop, you might be able to find a better selection of one or the other.