I'm surprised how much better Sly 2 gets the further I get into it. I think it's at gothic episode (episode 4?) it suddenly becomes much better. The hub is bigger challenge and more interesting to navigate, the missions you do are more fun, and the story takes some interesting turns.
I do agree that playing as Bentley and Murray isn't as fun as Sly, but I thought they handled it pretty well overall, especially with Bentley. He usually gets puzzle-esque missions or shoot'em'up stuff, both I think are fun and a nice change of pace. Murray gets too many simple brawl-em-up missions early in the game, but he gets much more interesting ones later on. It's also worth mentioning that later in the game there are less missions where you play as Bentley or Murray.
As far as I'm concerned, there's 3 things which makes Sly 2 much much better than the first one:
-Non-linearity! I love exploration in games, and I really hate feeling like I'm being led through a long corridor so this is a huge plus for me.
-More focus on stealth. It's almost nonexistant in Sly 1, and I thought they handled it very well in Sly 2.
-More puzzley stuff. Puzzles are always good! Even though they are mostly simple. But there are some clever puzzle stuff with Bentley, or stuff like figuring out how to navigate through a room without being detected as Sly.
I'm surprised how little I remembered of Sly 2. I remembered the first 2 episodes extremely well, but after that it was a blur. I'm really excited about going into Sly 3. I remember enjoying it back when it was released, but I'm curious how it'll hold up to Sly 2 now as I'm playing through them all in a rather short timespan.
Also, is it just me, or is Sly 2 surprisingly similar to Assassin's Creed series? Focus on navigating city hub without alerting guards, having to escape from guards when being detected, random objects you can use for hiding, smoke bombs and other stuff. I think AC could learn a few things from Sly 2, although it would be difficult without making it abstract and seem out of place. For instance, I think running treasures to safehouse is much more fun than opening a billion treasure chests in AC2, but I can't see how they could implement that into AC while having it seem even remotely realistic. And I definitely vastly prefer the platforming system in Sly compared to AC. AC is just too automatic.