The new gallery feature in 2.5 is good, but not perfect. I have now the problem, that I want to describe what I did on the weekend, with some pictures attached to the post. If you just want to add all the pictures, you can just add the [gallery] tag, but this gives you all the pictures. if you want to split the post related gallery into, let's say three pieces, then you have to insert every picture manually. This is possible with 5-10 pictures, but with a large number, that does not make any fun.
Possible Solution: At the upload dialog for pictures you have three tabs, "choose files", "gallery" and "mediathek" (maybe the are different in the english version, I have the german one). If it is possible to insert all pictures in the "choose files" dialog which you just have uploaded, that would make life so easier.