It really depends on the plugin, but as this is an incremental update, I doubt it’ll break anything.
Three plugins the 2.5.1 update appears to break – sidebar widgets (the big kahuna), wordpress video and post2pdf
A fix for sidebar widgets would be a great relief!!
I installed upgrade with wordpress auto updater set on automatic and it deactivated every widget that was a huge time waste, besides breaking connectivity with above mentioned widgets – wow!
