DS is currently 20lbs and 27 inches (at 5mo). I saw the washpod at stores before DS arrived and thought it was a bit silly (we used an IKEA recycling tub for dd1 and dd2 since our house only has a shower)... but a friend gave us one as a gift and we thought we'd give it a try.
And ds LOVES it. Love love loves it.

Seriously, I think this has been the single best item of baby gear we've ever had (and this is babe number three, so far only the ergo has been more useful). I
can say that it's a bit difficult to get him out of the pod since he is a chunky babe and there just isn't a lot of room to get under his arms and lift him out. But other than that, the washpod has been awesome. He loves it, it doesn't take up much room in the shower, and I think it'll fit for a while despite his size.
Here's ds getting his first bath (
here and
here) in the washpod... I really wish I'd had it for dd2 as well!