I'm admitting this now. The Culling of Stratholme (CoS) instance in the WoTLK expansion is one of, if not, my favorite instance of the Northrend ones. Other players seem mixed on it, but I enjoy it. First, the lore aspect. Out of the Northrend instances, this one probably tells a story the best (the end of Pit of Saron) isn't far behind. As a disclaimer, I have not been to the Halls of Reflection yet. The other reason I enjoy CoS is the simplicity of the layout. You basically run back and forth before you follow Arthas around through town to face the main boss, Mal'Ganis.
What did this inspire me to do? Why, go back to vanilla and solo Stratholme of course! Part of it was just to see how this version of Stratholme looks. I couldn't really see, it was dark! Another reason was to experience a higher level vanilla instance, with the thin hope of a mount drop from Baron Rivendare, the final boss.
What was my take on vanilla Stratholme? It took awhile for me to complete, but I enjoyed the atmosphere of it. This version is supposed to look like a town that has seen better days, with it's former denizens roaming the streets as zombies and ghouls. There's also a section where the Scarlet Crusade, those pesky zealots bent on taking out the undead, hold fort. Running this instance solo as a decently geared 80 made this an easy run for me. However, if I were to run it with my paladin at the appropriate level (which I hope to do), it would probably pose a bit of difficulty. The mobs are plenty, and the bosses can provide some challenge to the uninitiated.
Overall, old Stratholme did not disappoint. It ties in nicely with the lore, the settings fit the atmosphere, and I picked up some decent loot to AH or vendor. I recommend running this one.