I would like to try and summarise what could be a never ending thread (and increasingly boring I have to say). The points below are not my personal opinion but I think a summary of collective thoughts on this particularly topic.
1. Recline during take off, landing and meals = no no
2. Recline during short domestic trips in daytime = no (have noted the traveler who might be on the end of a long international flight)
3. Recline slowly at times other than 1 and 2 = acceptable
4. Apart from 1 and 2 and observing 3, reclining is the pax's right as the airlines provide the ability to recline
5. Physically resisting a recline is not really acceptable (see point 4)
6. Domino effect is perfectly acceptable when point 3 kicks in and finally
7. If you really can't cope with being reclined on or are long in the legs, bad back or any other affliction, buy/select an exit row, Y+ or J seat