Slowcooker or from the oven?

Out from the depth in the cupboard came my crockpot it hasn't been used for a while so after a quick dust and rinse out I set about making a beef casserole with some "taste the diffrence" beef that had been lurking in the freezer (I did defrost it overnight)  we had it for dinner tonight after it had been cooking away since 8 this morning we ate at 5.30 in stock, onions,garlic,carrots,celery, tomato purée a small amount of red wine and a hand tied bunch of fresh herbs. 

It was ok meat a bit tough though. 

Here's the problem it just doesn't taste as good as when I use the same ingredients in a my well know cast iron casserole dish in the oven cooked on about 140c for about 4 hours.

The diffrence seems to be the gravy in the slow cooker it comes out quite watery and even a little bland. From the oven the gravy is thicker has much more taste and the meat is even tender. 

Am I the only one or is it my cooking. My reptoir of slow cooking recepies are very limited regarding the slow cooker but I have stacks I use for the oven one pot meals. I have tried chicken in the slow cooker children hated it and to be honest it wasn't great from the oven same dish children can't get enough. 

Reading this back it's starting to sound like a very middle class problem or something you might here in a very well know upmarket Supermarket. 

But I don't want it to become one of those gadgets that just sits I the cupboard gathering dust and it's very useful to have something straight to hand with a bit of planning if we have been out all day. 

Maybe I should invest in a couple of slow cooker cookbooks as a few more won't hurt in my vast collection I already have.