Is it safe to install or is it buggy?
What about the battery? Discharges rapidly?

yes but still under your risk, and it is easy installable.

better

in my case no.

Please ask in the main next time

You need to be more specific, which version.
If you are installing from maemo Extras, the application has been tested to great extent.
With Testing and Devel versions of application you are more likely to find a bug etc.
If you are not sure install from extras this is considered a more "stable" release.

As for battery do you want KP to overclock or just for it's features?
Overclocking as well as voiding warranty etc etc may increase battery comsuption depending on usage.
I use KP not to overclock but to have more stable Smartreflex, this increases battery life greatly.

wiki.maemo.org/Smartreflex
wiki.maemo.org/Kernel_Power
wiki.maemo.org/Community_SSU

sorry if I answer here but I don't know the link of the official topic.
I installed kernel power 50 stable, but I have some problems. Before uninstalling it I prefer to see if they can be solved.
1) camera doesn't work anymore. When I open the cover says operation failed. I already did
sudo gainroot
apt-get install fcam-drivers
no success
2) I installed kernel power in order to make cleven work. but still says that the kernel version for injection drivers is not compatible.
I would appreciate your help
Thanks

Just a quick question: you do know that after installing Kernel Power, you have to select to boot your N900 with it, right (from power-off state, you slide out the keyboard, press power button to turn it on, and then there will be a selection screen)?

In your current N900 state where you are reporting errors, can you open Terminal and type this (then press Enter):

EDIT: not sure if you already uninstalled your Kernel Power though, based from your latest post...

still I don't uninstalled it: instruction are quite complicate to do that.

About what you said about the boot, I switched off and on the device, not booted as you said. I have no selection choice as you said. Maybe you are talking about the multiboot package? I did not use it. I just followed the instructions on the wiki page. From xterminal I checked
uname -r and kernel power is installed. But I cannot take any photo anymore. Further cleven (which was the reason why I installed the kernel power, not to overclock) doesn't work.
Now what I would just have is the camera work. I uninstalled and reinstalled fcam-drivers, I uninstalled bless900, still doesn' work.

update: I succeeded in making work the camera. The problem was that when I was installing the fcam-driver it was taking 1.06 version because I usually have just extra repository enabled. I enabled devel repository and I could install version 1.07.2.
even cleven problem was solved. The version in extra was too old.

you only have a boot menu if you have multiboot/uboot etc installed.

When I had the old fcam-drivers 1.06 I had an entry in the Application Manager. I uninstalled them with CleaN900 and then I installed the very new drivers. Everithing looks to work but the entry in Application Manager (under Uninstall) is disappeared. Did I anything wrong?