I had a lot of fun with Skyrim and I have something like 250 hours in it.
However, I think Skyrim has taken a few backwards leaps compared to earlier entries. While Skyrim is definitely bigger and better on a technical scale (gameplay mechanics, graphics, etc.), it is sorely lacking in comparison in customization and story.
Here's an example.
Morrowind Weapons Skills:
Spear
Axe
Blunt Weapon
Short Blade
Long Blade
Hand-to-Hand
Marksman
Skyrim Weapon Skills:
One-handed
Two-handed
Archery
Skyrim's "single player MMO" stylings are a blessing and curse. While it does add a ton of quests and activities, there's not much heart in it. There are a lot of cookie cutter quests of "go find this/kill this person at x dungeon" and activities like "cut all this wood or pick these crops" that really seem to artificially add time.
This more of a subjective complaint, but I would also say there's less freedom overall. Sure, there's a bigger world and more dungeons, which is what most people think when they think freedom. In the olden days, you could kill anyone, unlock any door, explore a dungeon any way you wanted, etc. Sometimes it would break the main quest line, sometimes it lead to alternative story paths. In Oblivion and Skyrim, NPCs are essential, there are unpickable doors, dungeons can only be completed one way, etc.
There's also Bethesda's lackluster patching that happens with every single one of their games. The large number of bugs is to be expected in a huge game, but that excuse only takes you so far when it takes unofficial community patches to eliminate all the bugs the devs didn't bother getting around to.
While it deserves a lot of praise, I think it's a tad overrated in that regard.