Tancredo's guest workers can only work in the USA for 1 year out of any two years. They cannot adjust to Permanent Resident Alien status, their US-born children are not citizens, etc.
The rest of H.R.3534 contains, as you mention, a lot of enforcement provisions, including workplace verification, that will do more to reduce illegal numbers than deportation ever could (though Tancredo also calls for doubling detention capacity).
The bottom line is that Tancredo is a restrictionist who calls for far lower overall migration levels and a time out from the massive third-world population transfers we've had the past 25 years or so. Voting for Tancredo is a shorthand way of telling open-border advocates why they've lost your vote.
The reason Tancredo's bills are not sailing through Congress is that there are a lot of Democrats and weak Republicans in office. Even so, I imagine that if Bush and Rove, instead of trolling in Tancredo's district for primary challengers, instead championed his bills - some would become law.
I guess I have always viewed this behavior as analogous to holding your breath until you turn blue - it doesn't accomplish much in a positive way.
I don't agree with Bush on some things, and I do agree with him on a lot of things. But he is light years closer to my positions than any of the possible Dem replacements. If I decide to make a protest vote, it will be in the primary - in the general election, I am voting for Bush, because any other vote, or not voting, is just a vote for the Dems - as we saw in 1992. I am not willing to put our country through that again, just because Bush doesn't do everything exactly the way I want.