Not as bad as you might think. I replaced the passanger mirror on my 97, without too much difficulty.
If memory serves me, the things that slowed me down:
1) Screw under the light panel on the lower door. (couldn't find it)
2) Actually tring to remove the door panel. The catches on the top of the skin can be a pain to pop off. (Where the seal at the bottom of the window is...) My advice...Don't remove the panel, just lift it up. You'll have to have someone hold the mirror on the outside of the door unitil you get the bolts started, unles you have 6 foot arms.
3) Very tight quarters to get at the bolts. Think '4000' 1/32 turns at a time.
4) The mini cover under the door handle. Once I removed it, it loved to pop out periodically. I swear i didn't break any tabs off. but it still loved to drop out whenever someone slammed to door to hard.
Proud owner of 'Quicksilver'
Currently Own - 2000 Bonneville SSEi, 70K, Silver (the fastest color)
Factory Options: all, except seat heaters (See Below)
Mods: Custom Seat heaters, GXP Strut Tower bar, Solid Engine mount (Alum Roundstock/ tire sidewall hybrid), Intense FWI, Intense 3.4" Pulley, Over-size Idler Pulley (for stock superchareger belt size), Mr. Alternator power source (Powder Coated Red), Belden Wires, Red Wire Looming, Autotap OBDII Gauge.
Appearance Mods: BRIGHT Red Brake Calipers all around, Cleared Corners, GXP Tails, Red Wire Looming, 17" Chrome 5 Spoke Rims
Next Mods: Intense PCM and Stage 1x Cam