I love my early 2011 Macbook Pro, but with only 4Gb of RAM it used the swap entirely too much and switching tasks could be slow. Also, the 5400rpm 320gb hard drive was slow for someone used to fast desktop drives. So I swapped them for 8Gb of ram and a 256Gb ssd, both from Crucial.
Smooth as silk. The macbook's guts are very cleanly laid out, and iFixit's extremely detailed guide let me know exactly what to do and what to expect every step of the way. The 54 bit toolkit itself is a pleasure to use.
There's tremendous power lurking within the 2.3Ghz macbook pro, but it does need 8Gb of RAM and an SSD to fully realise it. The upgrade is easy if you use the proper tools and guides, RAM is dirt cheap and SSDs are getting cheaper every day. This upgrade is an absolute must.