I consider it a DIY project myself. However, it may be more ambitious than it seems at first.
Gas line work.
Electrical wiring for high heat environment
Modification of fireplace and/or gas log
Possible flue revision
Several building authority inspections
Whether this should be a DIY is determined by obtaining and understanding the "building authority" requirements and regulations for your location. Maybe they say that a NFI professional must do the work. Or maybe they say "all work must be to X standard and inspected by Y".
This page suggests buyers look for an expert who is certified with the National Fireplace Institute.
We recommend you look for HVAC professionals, fireplace installers,
plumbers and chimney sweeps that may be listed at the NFI.
It is highly recommended that you have your chimney cleaned thoroughly
before you install your gas logs. It just so happens that many chimney
sweeps are also qualfied to install gas logs and, in most cases, are
eager to offer you a great price on the gas log installation if you
are also having your chimney swept. So look for a qualified chimney
sweep if you want to kill 2 birds with one stone and save some money.