Hi Paddy - I am definitely enjoying the game. It's a great puzzler that adds an interesting twist on the Tetris-clone genre, particularly in terms of atmosphere and presentation. I love the detailed backgrounds, audio and artwork.
Regarding the crashes that people have reported, it seems that I may have spoken too soon before - I had 3 crashes last night.
Each crash occurred while on the loading screen for a newly unlocked level in story mode at about the level 4-6 stage.
The crash resulted in the game and PSP freezing (the little spinning 'loading' block in the bottom left corner of the screen would stop spinning mid-load). It wasn't possible to return to the XMB. The only way to recover in each case was to turn off the PSPgo, which resulted in a hard reboot of the device.
When returning to the game after each crash incident, I would find that all my progress in story mode had been lost and I needed to start again from the beginning.
I noticed that the default setting in the game is for autosave to be off, so I always turned it on via the options menu before playing the game. When progressing through the levels in story mode, the game appeared to be saving my progress after each level. However it seems that when the game freeze occurs all progress is lost despite having autosave enabled.
I find it a little odd that the default is for autosave to be off though. Is this correct? Or could it be that the autosave is actually 'on' when the GUI indicates that it is 'off'? If so, this might explain why I had no progress saved after the crashes/reboots even though I thought I had turned autosaving on (and I had actually turned it off)?
In case it matters, my PSPgo was fully charged at the time.
Congratultions on the great review on this site!