Lesser quality how?
If you are referring to the tools, filters, file formats, etc of iMovie when compared to Premiere, Avid or FCP then that isnt 'lesser quality', more like 'feature lacking' or not as 'in depth' of an editorial program, but not lesser quality.
$20 says if you took the same content and video assignment, and gave it to 2 people, with one being experienced and using iMovie versus a noob editor using Premiere, the edit that was created in iMovie would look much better. Why? Because a tool is only as good as the person using it.
Does Premiere and FCP give you more controls for filters, titles, round tripping with other programs (color correcting, VFX, etc) yes! of course!
The op simply wants to start editing.. iMovie is just fine..
Not to mention if I import an h.264 file into both imovie and premiere.. create a few edit points, apply some simple color effects and export, they would look identical.
It all depends on the user and their comfort level. Its not the program.. its what you can do it that is fulfilling.