Pohnpei got what was probably my main benefit which was to have to carry less, I've watched backpacks just get bigger and bigger and I think it leads to a lot of problems for kids, especially small ones lugging that thing around all day.
I tend to be very skeptical of the other benefits because, even though it is easier to access more information, I don't think that students are necessarily any better informed or more capable of synthesizing information than they were before all the electronic aids appeared.
I'm assuming that we're talking about educational benefits here -- not social ones.
Educationally, things like Kindles or pad computers would make it easier for students to have access to various kinds of information. In that way, they are really helpful in the same way as computers and the internet, but somewhat more so. To be able to carry all your textbooks around in one small electronic device would be a blessing.
So, these devices are mainly useful because they make it easier for students to access information.
This is one of those "educational battlegrounds" that gets fought over and over during staff meetings across the country. As such, it can be a tough one to answer.
There are two problems, here. First, what is meant by an "electronic device?" I am guessing that you are referring to "personal electronics" such as cell phones, iPods, iPads, the Kindle, and not computers. I think it has been pretty well proven how computers can have "good" effects, so I think this is a safe bet.
Secondly, you would have to figure out what a "good effect" was. In the context of school, we can assume it means "an effect that makes learning more likely." Still with me? Your question specifically is asking for "good effects," which as any grouchy old teacher could tell you are harder to come up with, but I'll give it a shot.
Cell phones are an integrated part of our society at this point, and their main use is communication. They keep students in touch with the rest of the world by giving them the power to interact with it. In my day, if you forgot your lunch you were at the mercy of the office calling home for you. Now, students have the ability to solve their own problems and handle certain "emergencies" on their own.
Cell phones also allow students the ability, when the time is right, to keep in tough with students at other schools or friends that don't go to school. While not an educational benefit directly, better relationships can lead to higher self-esteem and reduce isolation, which is good for everybody. In the same way, camera phones allow students to capture the kinds of memories that help build a solid school culture, and, in some cases, can act as documentation of misbehavior in the same way that store cameras provide evidence and deter bad behavior.
Academically, the cell phone can act as to record video of a procedure or explanation that may need to be reviewed later. It could be used to record audio of a lecture, as well, for later review. And just imagine if class could be easily "taped" for students who are absent? What if they could even be streamed and seen from home instantly?
The iPod is a little trickier, because its function varies greatly by model. At its heart it is a media player, and I know for a fact that many students work better while listening to music. For this reason, they can have a good effect by keeping students from getting too distracted while working (ironic, because we mostly think of them AS distractions!) If it is a WIFI compatible model, and wireless internet is available, the iPod can be a great tool for looking up information or digging into things more deeply. Depending on the model, it may be able to act as a camera and video recorder as well (with the same benefits as the cell phone.)
Devices like the Kindle could, conceivably, make learning a lot easier. Imagine carrying all your textbooks in the palm of your hand, rather than strapped to your back! Though expensive, compared to buying new textbooks, the Kindle is a bargain. Many of the books used in high school English classes are actually FREE on the Kindle.
These are just some of the positives. Though most conversations seem to focus on the negatives, personal technology is here to stay and the sooner teachers learn to embrace it the sooner the benefits can be realized.