The verdict of the AMPS review:
"German Hanomag Sdkfz 251/1 (six figures) -- Poor. While always a popular kit, Tamiya chose the C model which was not common, and this kit also has a number of major errors such as being too narrow. Making this into a good model takes a lot of work."
Tamiya has also released the Sd.Kfz. 251/1 Ausf D as a separate kit (accompanied by four Panzer-Grenadiere), as kit nr 35195. Verdict of the AMPS review:
"Mitteler SPW Sd.Kfz. 251/1 Ausf. D (four figures) -- Very good. The ""Stuka zu Fuss"" with new figures and minus the rockets."
I am building this right now, one of my first kits after returning to the hobby after a 6 year absence, and the first to be painted by air-brush. So far it is a joy to build. I have encountered only two points were I needed filling (the other one was my own fault)., which was easy to do... so far all has fitted perfectly. I have also screwed up the placement of one of the gunracks, which needs to be taken out and replaced by a new one

... (here comes my first scratchbuild I guess

) Decals and paintschemes provided are for three different units:
5. SS Pz Division "Wiking" in Warsaw, August 1944 (in 3 color scheme)
Unknown unit, Eastern front, Winter 1943 (yellow base with brush painted white)
Unknown Unit, Normandy 1944 (in 3 color scheme)
I have seen aftermarket sets by Eduard and IIRC Aber. Tracks I have seen by Friul. As there is no engine included (unfortunately), if you want too show one , Verlinden has an update set for the Sd.Kfz. 251/9 Ausf D by Tamiya (nr 35147) which includes an engine, and possibly Royal Model.
I am thinking about building a new one in a few months using PE and an aftermarket update set and tracks...
Edit Also, read the post by Bison 44, my guess is many quetions about this kit will be answered..