I think that the SD slot was a much more practical move than the ExpressCard slot. There are FAR more people using SD than buying ExpressCard devices, and you can always get a cheap reader for MemoryStick or CompactFlash.
As far as the non-removeable battery--the writing was on the wall with the 17" MBP (late '08) that all Mac portables would follow. This is a good thing, considering Apple is doing the majority of the engineering work on the battery cells themselves and not leaving it to the likes of Sony (warping/exploding cells, anyone?). This gives them a lot more control over what goes in the computer, how it is charged/discharged, replaced, etc.
However, I confess that I would like to see the track-record for these new non-replaceable batteries for the next year or two before I decide to jump on board. Sure, you get a lot more longevity, but lets see how well they do before we take Apple's word for it. In other words, trust

but verify
Despite having just bought a [then] top of the line 15" MBP (2.66Ghz), I'm happy to see how they have refined the product line and dropped the price. If I were to buy another notebook today, it would be a lot more clear about what model I want; there were a lot of gaps and himming/hawing over "should I get 'this' with 'that'....or get 'that' with 'this'?"
Now you can get a 13" MB or 15" MB that are more alike with more appreciable differences (ie. screen size, discrete GPU/VRAM, battery life, SD slot, etc.etc.) It would be a lot easier to recommend a Mac laptop to someone 'now' with these choices, than it would have been earlier.