Yes, opinions on UGfs vary. Some people hate them, others like to use them as an additional filter type. I would never use one all by itself, and always in the past have combined them with a hang-on-back filter. Whether you use a UGF or not, a Python (or some other gravel cleaner) is a VERY important part of tank maintenance.
Having said that, IF the OP goes with his UGF I would absolutely suggest a powerhead. An air pump might do an "ok" job, but with a UGF you need a "better than ok" job. A powerhead will pull crud into the gravel much faster, and do a VASTLY much better job of preventing a buildup of crud underneath the plate. That buildup is one of the reasons that people who do not like UGFs do not like UGFs!