The blood throne is the first of the chariots that have distinct entries in the codex. As a 12 12 10 3HP thing, it is somewhat fragile and likely to be taken down with a few hits.  But equally, its no worse than a rhino (apart from the open top aspect of course), and we still see many a rhino on the battlefield even in 6th edition. For it to be fully effective, the blood throne needs to be up