Ok, so after a week of eating those shakes here's thoughts. (Just in case it's helpful for anyone else)
I did loose - about 7lb. Obviously being first week it's always a big loss from simple change of intake.
I tried the Original Honey and the Chocolate - not a fan of fruit shakes so didn't try the strawberry. I prepared them with almond milk and the original flavour with cold pressed rapeseed oil (it had the lowest saturated fat content I could find). I used a PhD Woman shaker as it had the little internal whisk ball, which the Yokebe shaker didn't, but didn't have any problems with the powder not incorporating at all.
They tasted funny at first, there was no problem with powderyness or bad tastes (inital taste was nice for both) but there was an unusual after taste. I got used to it by the second/Third day. I found it was much easier to drink them with a straw.
I didn't feel hungry at all - the shakes were very filling, and as they recommended I had snacks between - fruit, lean smoked ham (I found I was craving salty/savoury things quite heavily) Light and Free yoghurts and Tescos Healthy Living soups - I didn't feel too much like I was restricted.
For a few days on starting I did feel a bit sick, but I can't say for sure it was the shakes. I'd had a headache for a few days when I started (my usual summer/sun woes) and it could have been down to that. I felt better after a couple of days (which coincided with cooler, cloudier weather, so it probably was my summer allergy).
Only having the two flavours was somewhat boring, but generally yes, they were great. The lack of cooking and washing up was utterly blissful too.
They also seemed to be cheaper than other brands, and without loads of wasteful packaging.
Now that I know I'm ok with the meal replacement type diet (actually kind of love it - I loathe having to deal with food), I've ordered more online from a brand with more variety and completely recyclable packaging. But if they turn out ineffective I'd be alright going back to the Yokebe.
Hope this helps someone - it's amazing how little info there was on the net.