So I gave in and upgraded to PL6 Bartlett.
It's pretty good with a few teething issues so far. Lighter and quicker than PL4 Comice that I ran previously, there's a few cosmetic tweaks in the menu bars, plus Dockey (the dock application) has been replaced with plank because of it's very low overhead. Plank is much less refined, but does have a much lower overhead. All round it's been sped up generally, and apart from start up it feels quick zippy.
Problems? Well it wouldn't play DVDs to begin, all down to libdvdcss. The library containing a version of libdvdcss was installed, but didn't seem to be working (even though it had worked in PL4). Downloading libdvdcss2 fixed that, though playback glitches with a very brief pause about every 7-10min. Also mouse scrolling was reversed by default (like Apple's un-natural scrolling that I understand was a feature of Lion and ML) and the switch to undo that 'feature' wasn't obvious (hidden in pear tweaks applet). the appstore was also temperamental, sometimes falling over if 'pushed' a little.
Is anything new?
There are native apps for facebook, G+ and twather. Never thought I'd care, but it's nice to have 2 less tabs to keep open or hunt for in firefox, and although they aren't the greatest interfaces, it's still less effort than firing up a browser & then hunting down the page.
Also in the appstore was Calibre, which is a program for importing and converting ebooks between different formats, loading them onto readers etc. I've not tried it yet, but those who use it consider it essential for ebook reader owners, and since we both have Kobos it should be handy.
Worth mentioning that icons and text etc have been crisped up a little, each iteration making linux better and better as an operating system. It's not that icons or fonts are a really big deal, but having a crisp, well defined display takes a degree of strain out of use and generally helps the user to settle and work more efficiently. Maybe it's because I spend more time in from of non-windows computers these days, but I don't find W7 especially nice to use, though XP is still pretty much the benchmark in efficiency and user-friendliness. I would be happy to use pear Linux as my everyday OS now, and that is a huge step forward compared to 2 years ago.
So if you're a windows user and want something that has a Mac-ish look and feel, but runs lighter & quicker and with fewer design flaws (and less features, granted) PL is only an 850Mb download away.
32 bit (as I'm running now) and 64 bit (as I'll download & migrate to shortly) here: http://pearlinux.fr/download/