Disclaimer: I have been in the depths of thesis-draft writing, so I believe that around 60% of my angst is an extremely acute case of senioritis. However, the other 40% is founded on actual frustrations with academia, which I am working on articulating bit by bit.
I just got back from my last conference as a grad student. There were several papers I thought were really neat, some great talks, and lots of fun people to hang out with, which definitely made it worthwhile. But conferences have their share of frustrations (which led to me tweeting, at one point, "Academic conferences should provide more of a venue for punching people in the face".) I think some of these frustrations would be less significant if CS were journal-driven like almost any other field.
This has been well articulated by Lance Fortnow in "Time for Computer Science to Grow Up" (pdf). He reasons that the quality of publications would increase if we moved completed research to journals, and that using conferences as endpoints simply detracts from the main purpose of conferences: to bring people together. I'm not sure about the former, since others have pointed out to me that some flaws he mentions (biased reviewers, overspecialization, sloppy pre-deadline rushes, publish-or-perish, etc.) exist regardless of publication model. But, I think there are some things to be said for modifying the model just so conferences will be more fun.
And I'm way more concerned with how much fun our field is than its publication quality.
Most conference talks suck. It takes a huge amount of time to make a quality presentation, and there's little incentive to do so. Unless your talk is just plain offensive, the worst outcome for a thrown-together presentation is that people will forget it. For posterity, there's a good chance the line on your CV for the publication is all that matters. Yet, if you get a paper in a conference you're typically required to give a talk, so we end up with a lot of mediocrity. (Panos Iperiotis proposed having peer-review for talks, which sounds great in theory, but good luck finding enough people for that review committee.)
Poster conferences like NIPS avoid a lot of that, but conference attendance is expensive. And it's a shame that people should have to pick what publication to submit to based on where they can get travel visas.
Journal-driven fields treat conferences like our (less-well-attended) workshops, which seems more appropriate. CS conference talks leave little room for discussion. Difficult questions are typically perceived as an attack, tabled with "That's a good question! Let's discuss this offline". After all, the paper has already been published in essentially final form-- what's the point in arguing with the authors except to make yourself look smart? Furthermore, if one does have a significant issue with a paper that they'd like to address in the public forum, there's no "letters to the editor" section as in several journals. There's only Open Mic Night, and most of the audience is either checking email or leaving to go see a talk in a different track.
I'm sure there's a joke about how the super-introverted CS crowd wouldn't go to conferences unless they had to. But overall, I think the conference as the end point of publication creates a high-pressure situation that detracts from the open forum it should be, and makes attendees less sociable.
In lieu of changing the model, I would advocate each conference having a Punch-People-In-The-Face Plenary Melee.