i used glasses direct about a month ago for two pairs, and I've got a small prism of 1.5, as well as cyl of -2.5 in one eye. They phoned me up to double check I hadn't made a mistake and asked if I'd had one before. As soon as I said it was the same on my old glasses, they were fine about it.
I tried around 8 pairs free of charge before choosing the style. The only issue is getting a tight fit - they give instructions but I still found it difficult so had to take them into specsavers who adjusted free of charge.
If you can stack offers you get a good deal. I got two pairs for around £80 with the anti glare lenses. The same at specsavers were £160.
Oh, and delivery was slow, took around 3 weeks in total. One pair came with a slight blemish, so I sent them back and it took about 10 days but they exchanged without question and free postage.