I may be the last person off this ship. But for any stragglers that find the wreckage of this conversation regarding this sunken boat of an operating system, these were our last words...
In a word, Mavericks sucks IF...you are operating on anything less than a 2011 MBP. There is no getting out of it. No MAC apologists can refute this, and no paid-by-the-company contractors who are paid to write positive reviews of their products (yes they exist) can refute it either. I have a 2.4 Ghz w/ 4 GB of ram.
My laptop was designed to run on Leopard, then Snow Leopard.
It is the OS that best runs my computer. Downloading Mavericks is like asking NASA to handle flying your RC plane in your backyard. It is overkill, will only lead to confusion and the complicated nature and structure of NASA's work would only slow down such a flight.
If Mavericks works for you on your latest iMac or recent laptop, good on yer. But to those like me who are happy with their old systems but always curious to see if they can get a little more speed, a bit more battery power - do not upgrade to Mavericks. It will be a decision you will regret. It will turn your beloved laptop into a basket-case dumptruck on the autobahn. And you will have to revert like I did. Which by the way, was one of the best days of my life to be free from the shackles of Mavericks. Oh what joy it was to have my computer boot up in under four minutes again! Back to my usual pre-Mavericks 30 seconds even! To have my 'Bounce' button back on Mail! It was a magical day...
So there you go. Final answer. Do not call a friend. Do not ask the audience.
DO NOT UPGRADE TO MAVERICKS.
Mavericks? What about Yosemite? My 2008 MBP (with 4GB ram) can run either one, it seems. Personally, I think Mountain Lion felt slower than Mavericks on the 2008 MBP. Really, I don't think Mavericks feels too bad on it considering, but I have noticed that Logic Pro is a bit slower (i.e. some songs that were close to 100% CPU use under Snow Leopard in real time now do trip up, but it's not like massively slower. It could be the ram thing. OTOH, I can run up-to-date software on it (e.g. I think Handbrake and XBMC stopped supporting Snow Leopard some time ago). I won't run Yosemite on it or my 2012 Mac Mini, though until they solve some of those horrible GUI issues (and I don't just mean "flat" but hard to look at) or until my software stops working (or rather updates to thereof).