The Tower was my very first woodworking project and I had no problems building it at all. The only tools I had at the time was a power drill and a $30 Black/Decker jigsaw. I had all panels cut to size at the store. Just don't make it out of 1" MDF like I did or it becomes too heavy to lift. 5/8" or 3/4" with lots of bracing should be fine.You can brace with 1x3 or 2x3 as suggested in the plan, but window bracing is easier than you'd think. Arrange the panels so that the top and bottom panels are surrounded by the front, back and sides (ie. dimensions of top and bottom panels is equal to internal dimensions). Cut 2 or 3 additional panels exactly the same size as the top and bottom for each cabinet and use them for window bracing.
The Towers are about 4 cubic ft and if you've never had speakers that size, it's hard to imagine. I've gotten used to large speakers over the past couple of years. I'd suggest you do a mock up with cardboard boxes first to see how they fit and look in your room.
Can't comment on the top end as I built the older piezo version. But the Tower offers excellent dynamics, forward presentation and good bass.
If you're interested, I can also offer my unofficial unendorsed upgrade path to the Theatre-3.
gar.