That’s strange. For me the melee defenders always go towards the gate (which by the way seems to not be implemented yet, as seen in the screenshot below; but I guess you knew that so no need to report it as bug just yet:).
I did however spot some other issues:
VCMI: http://i4.photobucket.com/albums/y104/Zamolxis/VCMI/VCMI%2007/2009-09-23_HeroBehindWallNoGate.jpg vs H3: http://i4.photobucket.com/albums/y104/Zamolxis/VCMI/VCMI%2007/2009-09-24_H3Siege.jpg
#36 - The upper wall goes over the hero and whatever creatures the defending army may have in the hexes from the upper row.
#37 - The visiting hero does not collect the best troops from garrison to fill in his empty army slots when the town is under siege.
#38 - The castle/central tower in VCMI is placed higher than in H3 (though if you look at the base, somehow the VCMI one seems more centered - Unfortunately I forgot to capture that in the shots, but you can see for yourself by loading the attached map in both VCMI & H3). So from my part this does not need to change, as the central tower looks now somehow better placed… I’m just not sure of it so I thought it’s best to report it.
#39 - The hero is placed lower on the battlefield as compared to H3 (look at the hooves of hero’s horse in the 2 screenshots). This has actually nothing to do with sieges in particular. It seems to be general for any battlefield, for both the friendly and the enemy hero (I just didn’t notice it before).
See the attached map to reproduce all of the above (for Inferno, not sure if valid for all towns, but probably yes).
#40 - Creature hit by Arrow Towers turns with the back towards the attack. It’s best noticeable if the first creature that moves after Arrow Towers is an enemy one. In this case, as seen below, our Sprite remained blocked turned in the opposite direction, from the moment they were hit by the Arrow Towers, until the Griffins finished their flight and it was our turn. You can use the attached map to reproduce it, if you first remove the purple visiting hero from the MapEditor so that you can fight the Garrison creatures (or else fix #37 so that the defending hero accepts the Garrison creatures in his army:).
And just for fun, check out also the upper tower gog peeking outside of the battlefield if I disable stack queue (result of bug #5):
i4.photobucket.com/albums/y104/Zamolxis/VCMI/VCMI%2007/th_2009-09-24_ShySprite.jpg
4th VCMI Tests.7z (9.95 KB)