Wanted: Large messenger bag

at the cheaper end of the scale, what about one of these;

http://www.michaellinnell.co.uk/?p=showprod&id=453

nb - there's a 50 quid minimum order so if might want to try a group buy with someone else...

I know theres been some discussion about these before but can anyone vouch for them being any good. Do they have an ajustable strap?