There's a pretty consistent design for the David Tennant tenure. But recently the boxsets are all over the place. Some metal, some compressed and plastic, some that are just regular DVDs.

It looks a little weird. I was just wondering how important consistency is with people when it comes to boxsets, and how you feel about the various designs.

Well except for the 50th special box set ( or the stand alone Day and Time disks) the BluRay boxsets have been consistent sizes it seems. I think the BBC are perhaps trying to get people to buy the BluRays, they are likely to start reducing the extras on the DVDs, till eventually they only have the episodes and nothing else.
Also the cases could gradually get worse for the DVDs too, maybe even no card slip on top ether?
Of course the classics will carry on on DVD as they are all SD except Spearhead from Space, although there is no reason why in the future it could be just as efficient for them to release the classics on BluRay by upscaling them and include some HD extras along with DTS HD audio?

As far as my collection is concerned I have 90%+ of Tennant episodes along with series 1 new who on VHS and many of the classics on VHS too. From the Tennant specials onwards I have some on BluRay and others on my Skybox still with the only doctor who DVDs I own being the beginning boxset. So my collection is very inconsistent and I would appreciate upscaled BluRays of the first 4 new who series so they will match the Tennant specials, Smith and Capaldi series.

I was in HMV yesterday and noticed every series has been redesigned to a slim case with new artwork and vintage doctor who logo....I kinda like it but would make me want to buy every series again! It did stop me buying series 8 though because it then didn't match the rest of my collection. For those who have got series 8 boxset, is it still a standard design and larger box, or have they compressed it to make it slimmer?

The DVD version is basically a regular DVD case with a card casing. I think the Blu-ray is the same, but twice as thick as usual.

https://www.youtube.com/watch?v=k8Y2bAuXm5g&t=130