I do have to say that this availability search is a bit unfair on the previous posters. There is usually quite good availability for the next few days, then it dries up and availability is good again a few months out. If you plan for a short notice two week holiday that means you could get there on Avios and then have to pray for return availability to show up.

There are some legitimate things to moan about for Avios (high fees/taxes, availability on holiday routes), but there are also lots of good things (tier bonus, route network).