"Bought this to replace a 'standard' model that had a dodgy 'snib' and the cylinder had failed. This is a monster of a lock so take care if you are fitting to a glass panel door - measure the available space carefully.
I have given only 3 for reliabillity - its only been on the door 2 days. It is a bit pricey.
Its actually quite easy to fit as the larger size and thicker metal means you are chiselling out some sizable bits of wood instead of fiddly little bits. It doesn't seem have a 'snib' feature to latch the door in the locked position (which has been a problem with the old one), and the key lock from inside feature is a reassuring one. Provided you have sharp chisels and some common sense this is well within the average DIY'ers range. The templates are a bit fiddly (note left and right fitting so be careful), and READ THE INSTRUCTIONS before you start.
"Nice lock, very sturdy and feel of quality. Quite involved to install which does make it solid. Ensure you align the provided template very very accurately though or the lock cylinder will be skew and is very difficult to cure as tolerances are tight. My only criticism would be while it does dead lock when the door is closed so the locking bar can not be pushed back the inner knob can still be turned so if a thief broke the window they could still gain access easily."