I recently finished reading this book by Peter Gentry and Stephen Wellum. In essence, the book is an attempt to show a 'third way' between dispensationalism on the one hand and a Reformed covenantalism on the other. If that immediately confuses you, think of it like this: this is a debate about how much continuity and discontinuity there is along the Biblical storyline.
For dispensationalists (although there are various flavours and varieties), there is a great deal of discontinuity. The way God deals with human beings changes over the course of salvation history. The discontinuity is greatest when we reach the 'new covenant' in Christ, when in the classical dispensationalist scheme the church is understood as a sort of parenthesis in God's plan, which is really still focussed on the Jewish people. For dispensationalism, the covenant with Israel and the covenant with the church are totally different things.
In the classical Reformed scheme, on the other hand, there is one covenant, and it is common to talk about the 'unity of the covenant of grace'. (Actually, on some versions of Reformed thinking there may be a couple of other covenants, notably the 'covenant of works' broken by Adam - but these are not hugely relevant here). This is why many Reformed folk are keen on infant baptism, and not keen on Christian Zionism - the covenant is the same, so if infants were circumcised they are also to be baptised, and the people of God is also the same, so non-Christian Jews cannot still be related to God via a different covenant with different terms (although the covenant of grace may still have implications for them).
Gentry and Wellum's middle way has a lot to commend it. The book itself I found quite hard going, but I think that is just because there was a lot of very, very detailed exegesis. I struggle with that level of detail! Actually, the book itself promised to be a mix of Biblical and systematic theology, but in fact it was almost entirely the former with a slight consideration of some of the headline implications for the latter. But that is by the by,
The system itself is clear: the Biblical storyline is driven by the covenants, which really are different (contra the Reformed), but which all point in the same direction (contra dispensationalism) and all find their climax in the death and resurrection of Christ. This is, I guess, a 'Reformed Baptist' hermeneutic, so it's no surprise I found it fairly convincing. One of the most useful points I took from the book as a whole is the nature of all the covenants as both conditional and unconditional. Whereas there has been a tendency to divide the covenants into those which are unconditional - God will uphold them no matter what - and those which are conditional - they depend on human obedience for fulfillment - Gentry and Wellum helpfully show that a large part of the narrative of Scripture is driven by the fact that all the covenants require human obedience, and yet underneath that requirement is God's sovereign determination to establish his covenant. It is the tension which this introduces, given the constant failure of the human partner, which drives the narrative forward, and is only resolved in the perfect human partner, Christ. This also helpfully highlights the need for a clear doctrine of Christ's active obedience.
On the whole I found the book more convincing when tackling dispensationalism, but that could just be my bias. I'd like to see more attention given to the implications of this Biblical Theology to Dogmatics/Systematic Theology. Maybe that would be another book; this one is long enough! But if you're up for a thorough examination of the issues, you could do much worse than this.