I actually had both this past weekend - one MHL in a bottle and several Guinness, in a widget can and on tap.
MHL - not as watery/bad as I recalled, but nothing special or remarkable, either. Straw gold color with little to no hop aroma. Very little hop flavor. No head to speak of. Slight malt profile with a small hint of a 'charcoal' aftertaste. One was all I needed.
Guinness - what can I say - it's a Guinness!

Dark, slightly ruby color. Creamy off-white head that never completely dissapated. Slight roasted flavor and that distinct Guinness 'tang'. Had a smooth, but not at all heavy, mouthfeel. I'll have another, please!
