I've noticed some of the blog feeds I read have started to use only partial posts or have had it for a while. For whatever reason you do this it makes me hesitate to read the full post having to do the extra step to go to your site and read the rest. Unless you have a good reason like Through the Interface has.
"Firstly I should apologise to those readers using RSS to access this site: I've been playing around with the configuration, to integrate FeedBurner but also to switch from publishing entire articles via RSS to publishing introductions - my posts are just too long, which seems to cause a problem for some RSS readers."
But other blogs that only offer a partial feed consider offering your reader at least the option to get a full length feed. It's a waste of time IMHO to go through the extra step and it will not make me visit your site more often. Better ways to get me visit your site is to link back to an old post or give me some other reason to visit the site.
Another reason why I think full length posts are good is that I often search among old posts in Google Reader and it only finds what is in the excerpt and thus makes harder to find what I look for.
Offer something like this:
Please share your thoughts. Would you like a feed with excerpts for this blog? Why do you think a partial feed is good?