I don't advise blending it as there should be a few lumps in it - there are oats in there - but - what I advise is that you mix your water in using a fork and give it a real good mix!
I try to squash the lumps with a spoon on the side of the bowl, then some of them dissolve..lol.. but there will still be some lumps as irish angel said they are the oats. xx
I alway blend mine - but use a good stick/hand blender in your shaker cup, not a big blender or liquidiser (too wasteful!). I used to like the lumps, but I've got so used to the lovely smooth creaminess of blended porridge now, that I don't think I could go back!
I like it lumpy & thick, tend to cook it longer than the minute so its sticking to the sides of the bowl and I make sure I chisel those bits off so there is no waste. I find its more filling like that and feels like I have a full tummy.