Finally got my hands on an actual L420. Our school is issuing them this year to those of us who had the oldest R60 machines that they issued. So, here is my my admittedly "off-the-cuff" impression of them. My sense is that they are a fitting follow up to a long line of "secondary" level machines going back to the, 300 Series vs. the 600, "A Series" as related to the original Ts, followed by the "R Series" vs. the Ts of that generation. Meaning a very similar level of performance without the extra level refinement both in terms of detailed features and build sophistication necessary for folks who carry their machines through airports on a daily basis. Of course that's what you save in that two/three hundred dollar difference.
Personally, I love that extra level of refinement, so that's what we've always used at home (or X Series machines), but fully understand that its really a very nice "compromise" machine for a public entity like a school district. At least this time, they didn't make the mistake of CTOing the machines down
to save a few bucks and thus crippling them! They bought our R60s with 512Mb of RAM, and 40Gb HDDs! Needless to say, that I did an "unauthorized" RAM upgrade within the first week of issue.
But back to your OP; it seems to be a very nicely put together piece that will last through lots of daily use for the next 4 years or so. I really like the KB and the general layout of the machine a lot, much more than the R60. The screen looks better as well, but I must say that my R60 had the worse screen I've ever seen on a ThinkPad! Things I don't like? The low resolution is a bummer. Don't like not having latches either. The styling along the sides reminds me a little bit of the "i Series" that were trying too hard to look like a "real ThinkPad", plus it's a bit thick for my taste.