Firstly, to the grammar commenter, some people online are not educated to proper grammar. It is counter-productive to belittle them for their lack of grammar. Usually it just means that they are poorly educated (not their fault) or still too young to know proper grammar (also not their fault). So please stop hating and be respectful enough to read his post and mentally correct it in your own mind...then respond to his question in your own grammar.
As to Magic The Gathering: Duel of the Planeswalkers, I think it was not designed for experienced players like the OP. It was designed to teach a simplified version of the card game. I am not aware of land-walk working incorrectly in the application, seems to work fine for me. Given the simplicity of the program I was also surprised that it often froze up my XBox 360.
Imho, the game left out deck customization for a few reasons. Firstly, to prevent new players from making non-functioning (mana screw, oops no land!) decks. Secondly, to prevent experienced players (like me) from editing the decks into unfair (but deadly) combinations for online play. Thirdly, some players believe that a truly good magic player can win with any deck.
I cannot count the times (in tournaments no less!) a bad magic player copied a 'killer deck' from a magazine and played it like a robot. These players pretend that they are amazingly skilled but are basically just copycats. To prevent this phenomenon WoTC enacted Tournament Rules, Construction Rules, and Errata Clarifications. Imho, deck customization is at it's best when a player designs his own decks with cards he prefers.
I think this game was designed for new magic players and intermediate magic players. If you feel that it has too many limitations, as I do, it is because you are likely an advanced player. For myself I wish I could choose which mana to tap manually when playing cards, and freely construct my deck.
I would prefer to play multi-color decks instead of the predominantly mono-color weenie decks this game presents. I would prefer to reduce the ridiculous amount of mana in all of the decks! Having too much mana is just as bad as getting mana screwed when you need to draw useful cards imho.
I only play the Black/Green/Red deck and the Green/Red/White decks against people online. They are the most intelligently constructed decks and offer the most variety. They are also the most powerful decks when their strategy isn't halted by mana screw while being pounded by a puerile mono colored weenie deck.
I wish I could just add a few cards to hose mono colored decks...and I don't mean those lame ass 'heal if they play ' cards. I want Circles of Protection, Wards, Creatures with Protection if I am going to play against a mono deck. I would also like to see Earthquake, Fireball, Shatter, Disenchant, Dark Ritual, Lightning Bolt, Ancestral Recall, and some Moxes and Special Lands.