Not really. They have the lowest number of enemies out of all the factions, and their two mooks look the same and basically do the same things, apart from spawning webs and annoying bees.
To make it clear, I enjoy playing collectors, I just don't think they have more diversity than any other faction.
LoL OK, if you want to take it that way.
Entire Cerberus except Dragoons ****** hides in cover all the time and Atlases are too slow to get anywhere.
All the Geth walk mindlessly at you with the speed of a snail and stagger you at any given chance. The only difference is the range (Flame Trooper&Bomber vs the rest of the faction).
Collectors and Reapers are extremely similar (you could liken Sion to Ravager, Banshee to Praetorian, Husk to Abomination, Cannibal&Marauder to Trooper&Captain, which leaves the Brute without comparison).
On top of all of that, all collector units can get possessed, granting them at least extra barriers if not additional abilities, and therefore an entire new dimension of play&counterplay. They also spawn Swarms and drop Webs.
The units in all factions? 5 in Collectors vs 6 in every other faction - much difference, very number, hurr durr.
edit: Cerberus has 7 different units, but hardly make up for that in the diversity department.