I'll need to see what 1st rounder is included before I can really judge it, but this seems like a good trade for what both teams are doing. The Mavericks add a strong defensive center next to Dirk (and Powell) and will be able to match any FA offers this summer (now, whether or not the direction their taking - continuing to build around Dirk - is smart is another discussion, but for the path they're taking this is a good trade). The 76ers get a first (maybe protected 2017?) from the rapidly aging Mavericks, a decent asset, and an expiring contract that they'll likely buyout in Bogut (which may help them save money because of how prorating contracts and salary floor calculations work) for a player that they didn't really have room/a future for.
Hopefully Bogut does get bought out, I'd love to add him while only losing a guy like Mickey or Young
Edit: Top 18 protection this year means it won't be conveyed until next year at the earliest (when I'd assume it will be lottery protected), which actually seems like a decent deal for the Mavs. If the 6ers are able to redirect Bogut for an early second it could be a really nice move