DML's Panzer III M/N kit is a reasonable model, although it is not particularly easy to build.  Some of the problems lie with the kit itself; and others are compounded by production modifications of the real tanks.

The kit is typical of DML, in that it is a mix of DML and Gunze parts; with a lof of the sprues coming from the DML StuG III kits.  This kit also has the "super detailed" DML Panzer III/IV tracks with cleats. This is the same set sold seperately.  No open horns on the teeth, but otherwise nicely detailed.

Oddly the kit has p-e parts for the engine intake screens, since these intakes were covered by armored plates on the Ausf. N.  The kit's side skirting is die-cut from thin (clear) acetate sheet, and looks good, although there is no bolt detailing.  The turret belt armor is molded plastic, and is typical for this kind of part: thick with a beveled edge. The stand off armor for the mantlet and driver's are is well done.

There is a lot of fiddly cutting and filling to be done on the hull and fenders.  If you follow the kit instructions to cut away one of the molded on Bosch headlight mounts, you will have a scar on the front right fender treadplate.  I opted to model a Panzer III N that was based on an earlier Ausf. L chassis.  This allowed me to keep the hull side doors and twin headlight arrangement.  This is where some specific references come in handy as tool locations, headlights, cupola hatches, engine deck and transmission hinges, and lifting hooks all vary slightly between Panzer III variants.

One major error is the size of the 75mm howitzer gun.  It looks more like 37mm.  This part is about 200% too small.  A new barrel can be taken from a StuG III, or from Italeri's Panzer III F/G which includes three different 75mm gun barrels.

The decal sheet provides two or three sets of markings, although at least one set, for a Kursk tank, is incorrectly identified as being Hungarian.

Depending on how much photo-etch you want to add, there are a lot of sets available.  Airwaves makes a basic tool clamp and bracket set for the Panzer III, along with a couple of other basic sets for the DML Panzer III and StuG III.  Likewise, Eduard has some panzer III p-e. Even the On the Mark set (made for the OLD Tamiya kit) has a ton of usable parts.  Some new tracks would not hurt, either, especially if you try to model an earlier version of the N.