Our experiences with Alpine's "mechless" car audio receivers have been mostly positive. So, when we received the, which ups the ante with the inclusion of a larger display and touch sensitivity, we naturally assumed that bigger would be better.
During testing, we found that everything that we liked about Alpine's single DIN mechless units was still intact in the W404, such as the snappy high-speed USB/iPod connection that allowed us to quickly scrub through large digital-audio collections using the double-action encoder. We also liked that the W404's larger screen and dedicated iPod video cable allowed the playback of movies and video podcasts from capable iPods.
However, the touch-screen interface is unintuitive at times, relying on an iTunes CoverFlow-like paradigm to navigate its menus. The additional eye candy of the interface seems to have adversely affected the Alpine's menu responsiveness when compared with its simpler siblings.
The unit features the capability to add modules to expand its admittedly limited feature set, but doing so can be prohibitively expensive. For example, it costs about $500 to add navigation ($300 for the GPS module and $200 for an adapter cradle to connect it) and $230 to add Bluetooth wireless, bringing your total investment to about $1,280. At that point, you may as well be looking at Alpine's superior IVA-W505/P1, which packs more functionality into a single box, without the need for additional modules.
If you want a simple, "mechless" receiver and can live without iPod video playback, we'd suggest you look at Alpine's single-DIN.