I'm not any kind of authority on amps, so I might not be the best person to ask, but I really like it.
I don't think the 5W Marshall was out when I got the HT-5, but I did try out an Orange Tiny Terror (which I loved!), but HT-5 was a lot more versatile with it's 2 channels and effects loop.
Never played through any big 100W Marshalls or anything though, so can't really compare to that.