(Viewliners are the single-level cars used on most routes east of Chicago, while Superliners are the double-deck cars used on the rest of the system. Viewliners operate on those routes where Superliners don't fit due to bridge and tunnel clearnce restrictions. See Amtrak's sleeping accomodations page for details, maps, and 3D tours of the equipment.)
My opinion overall: bedrooms are always better than roomettes (more room), and Superliner rooms are better than their Viewliner equivalents (less headroom but more usable space). The fact that Viewliner roomettes have a toilet and sink so you don't have to use the toilet down the hall is, in my opinion a bug, not a feature, because it uses up precious floor space in the compartment. On the other hand, the "attic" on the Viewliner cars (the area near the top of the higher-ceiling single-level Viewliner bedrooms) is quite handy if you don't have a problem hefting luggage over your head.
Any sleeping compartment of any size or configuration is superior to a coach seat. Oh, and any Amtrak coach seat is superior to any airline coach seat, while most airline first/international business class seats are comparable to a Superliner coach seat.