This is a particular post I've been wanting to add for awhile. Of course, I needed to upload the image so folks would know what I'm talking about, which means waiting till I had access to my own computer.
I think Mentzer's Expert set is great. Quite frankly, I believe I actually enjoy it more than the Companion rules, which were fairly indispensable to my original gaming group (though we were using them with AD&D...hey, it's not our fault AD&D blew off dominion and mass combat rules!).
As already stated in earlier posts, my first exposure to D&D was through the Moldvay/Cook Basic and Expert sets, subsequently followed by AD&D, subsequently followed by a decade+ hiatus from D&D in any form. However, I did go out of my way to collect all the BECMI books somewhere down the road...around my mid-20's actually. I did this for a specific reason: I wanted to complete the promise that was begun in Moldvay/Cook's B/X rules.
So I purchased the Companion set, I got my hands on the Master set, and eventually I found the Immortal rules. I figured I didn't need the Red and Blue boxes, 'cause I already had B/X, right?
Mentzer's Expert rules is pretty much the exact same as Cook's Expert set with only a few exceptions. One of those exceptions are more clerical spells (up through 6th level, I believe where the Cook set only goes through 5th). The additional spells presented in the Mentzer Expert set are present nowhere else (well, except the Rules Cyclopedia, of course). Once I discovered this, I made the decision to acquire both Mentzer's blue set and red set. Heck, I even got a second copy of the Expert book (total of two) as back-up.
I've never been disappointed.
Mentzer's Expert set is only 64 pages long, the same length as the original, and nicely layed out. Threshold and its sample adventures are greatly appreciated, and I can say (from a player's point of view) that it makes an excellent base of operations for a starting adventuring party...my old AD&D DM made plenty of use of Threshold, and I never realized she was getting it from her Expert set.
In 64 pages, Mentzer manages to include everything from the Cook edition (with the exception of the crowbar...dammit, why not, Frank?) plus adds extras like Threshhold and the additional spells.
It also has killer artwork. I like Elmore's artwork anyway (I was a big fan of SnarfQuest), but it can be grating and cheesy at times, especially the some of the stuff in the Red box set (a little too Dragon Lance if you ask me). The stuff in the Expert set, though, is pure gold in my opinion. The cover is my favorite of the BECMI series (possibly tied with the Companion cover). The character classes (especially the cleric pictures) look like "experts," not novices, and not high level master-types. For me, they really capture the mid-level adventurer...and make me want to play any of the classes.
Well, with one caveat...the pictures of the demi-humans. There really aren't any, at least none that are prominent. The one visible elf in the entire book is the girl on page 58...and she's not wearing armor? Excuse me, this is D&D, not AD&D...elves (especially mid-level ones) are going to be wearing at least leather or chain mail, don't you think? Why else are they splitting half their XP? What's with the Peter Pan outfit, missy? The dwarves are a little better, while the only halfling I could find (in the crowd on page 37) is...well, he doesn't inspire ME to play a halfling!
I don't know if the decision to concentrate the illustrations on "cool pictures of humans" was deliberate or not, but if the intention was to draw focus to the humans (for the high level play described in the Companion and Master sets), then mission accomplished. By the time I get to the fat midgets and leafy tights of the Companion set, I'm probably NOT going to be playing a demi-human. Thanks, guys.
But back to the praise...with regard to everything EXCEPT the demi-human artwork and the missing crowbar (and some blatant typos...yes, I'm looking at you page 23), I find Mentzer to be at least equal to the Cook set. Erol Otis and those other OS artists rock, but Mentzer's Expert book is the one I use as my "working" rule book when I'm playing B/X these days. It's great.