As far as regular use stability it pretty solid, I'd say my experience with it has been a lot more stable than Home++ and GDE. With both I'd get lag and a lot of FC when trying to go back "home". With SH2 going "home" is a bit laggy but definitely not an excruciating as the Home++ and GDE.
I tested my battery out today also. Regularly with moderate-light (texting, autoupdate of widget every few hours, no calls, and no GPS) I can get 12-15 hours with 40%-30% battery left. Today I got 17hours of moderate-heavy usage (about 2 hours of GPS using the navigator, a few short quick calls, checking news, auto updates with widgets) until it completely crapped out on me. So all in all not bad at all, Lasted me a day's worth without sacrificing any of my phones functionality. So the real culprits for battery drainage was probably the calls I made and GPS, other than that Sweeter home shouldn't really affect battery life.
As far as CPU usage, I did notice that under battery use it was up there in the list, I think it was 9% but went down to 3% after some time passed without using the phone. I think it just has to do when your actively using the phone. Under CPU usage in the Spare Parts app it was also up there in CPU use, total time of CPU use is a whopping 3 mins lol. But from my partial awake usage stats it wasn't even included in the list, so this means it wasn't working when my phone was on standby. Strangely enough facebook was, and I don't even have it set to auto-update :\
So, even though the CPU usage was a little bit higher it didn't really seem to affect my daily usage/battery life very much. Definitely worth a look for people worried about performance decreasing. The only thing that is really annoying me right now is my widgets getting "stuck" and sometimes not even showing up.