I hope it gets enough of a base to support it, but I also think it was a bit rough when launched. The picture quality of some of the programs is a bit dodgey. I am sure there is a technical reason for it because a lot of programs from the States seem to be that way if they weren't originally filmed in HD. Screen sizes or something.
Standard definition resolutions between countries broadcasting in PAL or SECAM (Europe, Africa, Most of Asia, Australasia & half of Latin America) and NTSC (North America, parts of East Asia, half of Latin America) along with the scan rate is the main reason - PAL and SECAM systems have a scan rate of 50Hz (25 frames a second) while NTSC was 60Hz (or 59.994Hz technically) (30 frames a second), reasons for this was to match the scanning rate to that of local electricity supplies to avoid rolling pictures and flickering when technologies of the 40s and 50s were less advanced. PAL & SECAM in nearly all places had 576 visible horizontal lines from 625, NTSC only had 480 visible horizontal lines from 525, this meant PAL/SECAM pictures were about 20% sharper than NTSC. There were/are also other technical considerations that I won't go into detail, but it meant that in the past you could easily tell an American (or NTSC) sourced programme in that it was at times a little blurry as it was less detailed and that due to the scan rate difference PAL & SECAM seen every sixth frame from the NTSC source dropped, but the colour also looked that little bit "warmer" as well. Early colour conversions were fairly primitive, for example the 1968 Olympics in Mexico were sent via satellite to Europe, picked up at the BBC, displayed there on an NTSC monitor and a PAL camera pointed at the screen did an optical conversion for viewers watching around Britain. Electronic conversions came a short while later.
These days with high definition there is a common line standard of 720 and 1080 worldwide now, and colour rendering is now effectively the same as PAL, SECAM and NTSC were systems that dealt with handling colour for transmission in analogue form, each of them slightly different and incompatible. Differences in scan rates still exist due to legacy, but most TVs now can display a wide variety of them starting at 24fps to 60fps, either progressive or interlaced. The old characteristic that American pictures had when shown on British TV's when it comes to HD now is difficult to spot.
Just for reference, when analogue TV stations did (and still do in some places) broadcast big films, or they were played on video tape and DVD, they were often sourced from a reel supplied from the distributor similar to that used in cinemas. These reels have (and still do) have a frame rate of 24fps as an industry standard. In PAL and SECAM countries, they just simply sped up the reel by 4% to reach 25fps, and the slightly higher pitch in sound as a result was not noticeable to most viewers, with the film being slightly shorter as a result (a 100 min film in the cinema would be 96 min on TV or VCR & DVD) - NTSC countries couldn't do this though as to match the 30fps rate they would have to increase the speed of the reel by 25%, causing a very noticeable high shift in voice pitch and end up showing some scenes looking like it was the final bit of the Benny Hill show on 3/4 speed
so they had to have something called 3:2 pulldown which duplicated every fourth frame but had the nasty side effect of introducing juddering on screen. For many American TV producers, as most tellys there can produce 24 or 25fps nowadays, this is one less headache.
As for PBS UK, I reckon being a pay-only channel is a hindrance to getting bigger viewership as they have to stand out a lot to get noticed among the pile of **** that's on Sky and cable, were they free-to-air on satellite and had a place on the less cluttered Freesat EPG they could stand out more.